Derivatives
WEIGHTAGE : 17 MARKS
USING DEFINITION OBTAIN DERIVATIVE
• Find derivative of y = 𝒙
Here f(x)= 𝒙
Therefore f(x+h)= 𝒙 + 𝒉
Now according to definition of derivative
• f’(x)= 𝐥𝐢𝐦
𝒉→𝟎
𝒇 𝒙+𝒉 −𝒇(𝒙)
𝒉
• = 𝐥𝐢𝐦
𝒉→𝟎
𝒙+𝒉− 𝒙
𝒉
• = 𝐥𝐢𝐦
𝒉→𝟎
𝒙+𝒉− 𝒙
𝒉
×
𝒙+𝒉+ 𝒙
𝒙+𝒉+ 𝒙
• = 𝐥𝐢𝐦
𝒉→𝟎
𝒙+𝒉
𝟐
− 𝒙
𝟐
𝒉( 𝒙+𝒉+ 𝒙)
= lim
ℎ→0
𝑥+ℎ−𝑥
ℎ ( 𝑥+ℎ+ 𝑥)
= lim
ℎ→0
ℎ
ℎ ( 𝑥+ℎ+ 𝑥)
= lim
ℎ→0
1
( 𝑥 + ℎ + 𝑥)
=
1
( 𝑥+0+ 𝑥)
=
1
( 𝑥 + 𝑥)
=
1
2 𝑥
DERIVATIVE OF CONSTANT ( C )
• Find derivative of y =c
Here f(x)=c
Therefore f(x+h)=c
Now according to definition of derivative
• f’(x)= 𝐥𝐢𝐦
𝒉→𝟎
𝒇 𝒙+𝒉 −𝒇(𝒙)
𝒉
• = 𝐥𝐢𝐦
𝒉→𝟎
𝒄−𝒄
𝒉
• = 𝐥𝐢𝐦
𝒉→𝟎
𝟎
𝒉
• =0
Using definition find derivatives
• Find derivative y=3𝑥2
− 2
Here f(x)= 3𝑥2
− 2
Therefore f(x+h)= 3 𝑥 + ℎ 2
− 2
=3(𝒙𝟐
+2xh+𝒉𝟐
)-2
= 3𝒙𝟐
+6xh+3𝒉𝟐
-2
Now according to definition of derivative
• f’(x)= 𝐥𝐢𝐦
𝒉→𝟎
𝒇 𝒙+𝒉 −𝒇(𝒙)
𝒉
=𝐥𝐢𝐦
𝒉→𝟎
3𝒙𝟐+6xh+3𝒉𝟐−2 −(3𝑥2 −2)
𝒉
=𝐥𝐢𝐦
𝒉→𝟎
3𝒙𝟐+6xh+3𝒉𝟐−2−3𝑥2+𝟐
𝒉
• =𝐥𝐢𝐦
𝒉→𝟎
6xh+3𝒉𝟐
𝒉
• = 𝐥𝐢𝐦
𝒉→𝟎
𝒉(6x+3𝒉)
𝒉
• = 𝐥𝐢𝐦
𝒉→𝟎
(𝟔𝒙 + 𝒉)
• = 𝟔𝒙 + 𝟎
• = 𝟔𝒙
Using definition find derivatives
• Find derivative y=4𝑥2
+ 5x − 2
Here f(x)= 4𝑥2
+ 5x − 2
Therefore f(x+h)= 4 𝑥 + ℎ 2
+ 5(x + h) − 2
=4(𝒙𝟐
+2xh+𝒉𝟐
) + 𝟓(𝐱 + 𝐡)-2
= 4𝒙𝟐
+8xh+4𝒉𝟐
+5x+5h-2
Now according to definition of derivative
• f’(x)= 𝐥𝐢𝐦
𝒉→𝟎
𝒇 𝒙+𝒉 −𝒇(𝒙)
𝒉
=𝐥𝐢𝐦
𝒉→𝟎
(4𝒙𝟐+8xh+4𝒉𝟐+5x+5h−2)−(4𝑥2+5x−2)
𝒉
=𝐥𝐢𝐦
𝒉→𝟎
4𝒙𝟐+8xh+4𝒉𝟐+5x+5h−2−4𝑥2−5x+2
𝒉
• =𝐥𝐢𝐦
𝒉→𝟎
8xh+4𝒉𝟐+5h
𝒉
• = 𝐥𝐢𝐦
𝒉→𝟎
𝒉(8x+4h+5)
𝒉
• = 𝐥𝐢𝐦
𝒉→𝟎
(8x+4h+5)
• = 8𝒙 + 𝟒(𝟎) + 𝟓
• = 8𝒙+5
IMPORTANT FORMULAE FOR
DIFFERENTIATION
• If y = 𝑥𝑛
then
𝑑𝑦
𝑑𝑥
=n𝑥𝑛−1
• If y = x then
𝑑𝑦
𝑑𝑥
= 1
• If y=c then
𝑑𝑦
𝑑𝑥
=0
• If y=𝑒𝑥
then
𝑑𝑦
𝑑𝑥
= 𝑒𝑥
• If y= 𝑎𝑥
then
𝑑𝑦
𝑑𝑥
= 𝑎𝑥
loge a
• If y= loge x then
𝑑𝑦
𝑑𝑥
=
1
𝑥
RULES OF DERIVATIVES
• If U and V are functions of x then
y=u+v then
𝑑𝑦
𝑑𝑥
=
𝑑(𝑢+𝑣)
𝑑𝑥
=
𝑑𝑢
𝑑𝑥
+
𝑑𝑣
𝑑𝑥
y=u−v then
𝑑𝑦
𝑑𝑥
=
𝑑(𝑢−𝑣)
𝑑𝑥
=
𝑑𝑢
𝑑𝑥
-
𝑑𝑣
𝑑𝑥
y=u×v then
𝑑𝑦
𝑑𝑥
=
𝑑(𝑢𝑣)
𝑑𝑥
= 𝑣
𝑑𝑢
𝑑𝑥
+ u
𝑑𝑣
𝑑𝑥
Y=uvw then
𝑑𝑦
𝑑𝑥
=
𝑑(𝑢𝑣𝑤)
𝑑𝑥
= 𝑣𝑤
𝑑𝑢
𝑑𝑥
+ 𝑢𝑤
𝑑𝑣
𝑑𝑥
+ 𝑢𝑣
𝑑𝑤
𝑑𝑥
Y=
𝑢
𝑣
then
𝑑𝑦
𝑑𝑥
=
𝑑
𝑢
𝑣
𝑑𝑥
=
v 𝑑𝑢
𝑑𝑥
− u 𝑑𝑣
𝑑𝑥
𝑣2
Chain rule : If y is function of u and u is function of x then
𝑑𝑦
𝑑𝑥
=
𝑑𝑦
𝑑𝑢
×
𝑑𝑢
𝑑𝑥
If U and V are functions of x then (I)y=u+v then
𝑑𝑦
𝑑𝑥
=
𝑑(𝑢+𝑣)
𝑑𝑥
=
𝑑𝑢
𝑑𝑥
+
𝑑𝑣
𝑑𝑥
(II)y=u−v then
𝑑𝑦
𝑑𝑥
=
𝑑(𝑢−𝑣)
𝑑𝑥
=
𝑑𝑢
𝑑𝑥
-
𝑑𝑣
𝑑𝑥
Find
𝑑𝑦
𝑑𝑥
of the following functions using rule (i) and (ii)
(I) 3𝑥2
+2
SOLUTION :
I. Y= 3𝑥2
+2
𝑑𝑦
𝑑𝑥
=
𝑑3𝑥2
𝑑𝑥
+
𝑑2
𝑑𝑥
[∵ RULE (I)
APPLIED ]
= 3(2X)+0
=6X
(ii)4𝑥2
+5X+1
SOLUTION :
Y= 4𝑥2
+5X+1
𝑑𝑦
𝑑𝑥
=
𝑑4𝑥2
𝑑𝑥
+
𝑑5𝑥
𝑑𝑥
+
𝑑1
𝑑𝑥
= 4(2X)+5(1) +0
= 8X+5
(III) 5X-9
SOLUTION :
Y=5X-9
𝑑𝑦
𝑑𝑥
=
𝑑 5x
𝑑𝑥
-
𝑑9
𝑑𝑥
=5(1)-0
=5
Solve the following
(i) y=𝑥3
+ 𝑥2
+ 𝑥 − 2 (II) y=7𝑥7
+ 5𝑥4
− 20𝑥 +
37
• SOLUTION :
• y=𝑥3
+ 𝑥2
+ 𝑥 − 2
•
𝑑𝑦
𝑑𝑥
=
𝑑𝑥3
𝑑𝑥
+
𝑑 𝑥2
𝑑𝑥
+
𝑑𝑥
𝑑𝑥
-
𝑑2
𝑑𝑥
• =(3𝑥3−1
) +(2𝑥)+1-0
• = 3 𝑥2
+2𝑥+1
• SOLUTION:
• y= 7𝑥7
+ 5𝑥4
− 20𝑥 + 37
•
𝑑𝑦
𝑑𝑥
=
𝑑7𝑥7
𝑑𝑥
+
𝑑 5𝑥4
𝑑𝑥
-
𝑑20𝑥
𝑑𝑥
+
𝑑37
𝑑𝑥
• =7(7𝑥7−1
) +5(4𝑥4−1
)-
20+0
• = 49𝑥6
+20𝑥3
− 20
(I) y=u×v then
𝑑𝑦
𝑑𝑥
=
𝑑(𝑢𝑣)
𝑑𝑥
= 𝑣
𝑑𝑢
𝑑𝑥
+ u
𝑑𝑣
𝑑𝑥
II Y=uvw then
𝑑𝑦
𝑑𝑥
=
𝑑(𝑢𝑣𝑤)
𝑑𝑥
= 𝑣𝑤
𝑑𝑢
𝑑𝑥
+ 𝑢𝑤
𝑑𝑣
𝑑𝑥
+
𝑢𝑣
𝑑𝑤
𝑑𝑥
• Find the derivative w.r.t 𝑥
• Y= (3𝑥2
− 2)(𝑥2
+ 7)
• 𝑢 = 3𝑥2 − 2 𝑣 = (𝑥2 + 7)
•
𝑑𝑢
𝑑𝑥
=6𝑥
𝑑𝑣
𝑑𝑥
=2𝑥
•
𝑑𝑦
𝑑𝑥
= 𝑣
𝑑𝑢
𝑑𝑥
+ u
𝑑𝑣
𝑑𝑥
• =(𝑥2 + 7)(6𝑥) + 3𝑥2 − 2 (2𝑥)
• =(6𝑥3+42𝑥) +(6𝑥3-4𝑥)
• = 6𝑥3
+42𝑥+ 6𝑥3
-4𝑥
• = 12𝑥3 +38𝑥
• Find the derivative w.r.t 𝑥
• Y= (2𝑥2
+ 3)(3𝑥2
+ 2)(𝑥+7)
• 𝑢 = (2𝑥2 + 3) 𝑣 = 3𝑥2 + 2 𝑤 = (𝑥+7)
•
𝑑𝑢
𝑑𝑥
= 4𝑥 + 0
𝑑𝑣
𝑑𝑥
= 6𝑥 + 0
𝑑𝑤
𝑑𝑥
= 1+0
•
𝑑𝑦
𝑑𝑥
= 𝑣𝑤
𝑑𝑢
𝑑𝑥
+ 𝑢𝑤
𝑑𝑣
𝑑𝑥
+ 𝑢𝑣
𝑑𝑤
𝑑𝑥
=(3𝑥2 + 2)(𝑥+7) 4𝑥+ (2𝑥2 + 3) (𝑥+7) 6𝑥+ (2𝑥2 + 3)(3𝑥2 + 2)1
= (3𝑥2 + 2)(4𝑥2+28𝑥)+ (2𝑥2 + 3)(6𝑥2+42𝑥) +(2𝑥2 + 3)(3𝑥2 + 2)
= 4𝑥2
(3𝑥2
+ 2)+ 28𝑥 (3𝑥2
+ 2)+ 6𝑥2
(2𝑥2
+ 3)+42𝑥(2𝑥2
+ 3)+ 3𝑥2
(2𝑥2
+ 3) + 2(2𝑥2
+ 3)
=12𝑥4
+ 8𝑥2
+ 84𝑥3
+ 56𝑥 + 12𝑥4
+ 18𝑥2
+ 84𝑥3
+ 126𝑥 + 6𝑥4
+9𝑥2
+4𝑥2
+ 6
= 12𝑥4
+ 12𝑥4
+ 6𝑥4
+84𝑥3
+84𝑥3
+ 8𝑥2
+18𝑥2
+9𝑥2
+4𝑥2
+56𝑥 + 126𝑥+6
=30𝑥4
+ 168𝑥3
+ 39𝑥2
+ 182𝑥 + 6
NOW TRY YOUR SELF
• FIND DERIVATIVES WITH RESPECT TO 𝑥
• Y=(2𝑥 + 3) 5𝑥3 − 2
• Y=𝑥4
+ 𝑥5
+ 5𝑥6
+ 3𝑥2
+ 3𝑥3
− 9
• Y=3𝑥4 + 13𝑥3 − 9𝑥 + 15
• Y=(𝑥 + 1)(9𝑥 + 5)(𝑥2 − 9)
• Y= 3𝑥2 + 5𝑥 − 9
• Y=(𝑥2
+ 𝑥 − 1)(𝑥2
+ 𝑥 + 1)
• Y=(2X-1)(6X+1)
• Y=7𝑥2 + 123𝑥 − 100
Y=
𝑢
𝑣
then
𝑑𝑦
𝑑𝑥
=
𝑑
𝑢
𝑣
𝑑𝑥
=
v 𝑑𝑢
𝑑𝑥
− u 𝑑𝑣
𝑑𝑥
𝑣2
• FIND THE DERIVATIVE OF 𝑦 =
1+𝑥
1+𝑥2
• HERE 𝑦 =
1+𝑥
1+𝑥2 =
𝑢
𝑣
• LET 𝑢 = (1 + 𝑥) 𝑣 = (1 + 𝑥2)
•
𝑑𝑢
𝑑𝑥
= 0 + 1
𝑑𝑣
𝑑𝑥
= 0 + 2𝑥
•
𝑑𝑦
𝑑𝑥
=
𝑑
𝑢
𝑣
𝑑𝑥
=
v 𝑑𝑢
𝑑𝑥
− u 𝑑𝑣
𝑑𝑥
𝑣2
• =
(1+𝑥2) (1)−(1+𝑥)(2x)
(1+𝑥2)2
=
1 + 𝑥2
− 2𝑥 − 2𝑥2
(1 + 𝑥2)2
=
1−2𝑥−𝑥2
(1+𝑥2)2
• FIND DERIVATIVE 𝑦 =
𝑥2+𝑥+1
𝑥2−𝑥+1
• HERE 𝑦 =
𝑥2+𝑥+1
𝑥2−𝑥+1
=
𝑢
𝑣
• LET 𝑢 = (𝑥2
+ 𝑥 + 1) 𝑣 = (𝑥2
− 𝑥 +
1)
•
𝑑𝑢
𝑑𝑥
= 2𝑥 + 1
𝑑𝑣
𝑑𝑥
= 2𝑥 − 1
•
𝑑𝑦
𝑑𝑥
=
𝑑
𝑢
𝑣
𝑑𝑥
=
v 𝑑𝑢
𝑑𝑥
− u 𝑑𝑣
𝑑𝑥
𝑣2
•
=
(𝑥2−𝑥+1) (2X+1)−(𝑥2+𝑥+1)(2x−1)
(1−𝑥+𝑥2)2
=
=
Find derivati𝑣𝑒𝑠 w.r.t. 𝑥
• Y=
3
2−5𝑥
• HERE 𝑦 =
3
2−5𝑥
=
𝑢
𝑣
• LET 𝑢 = 3 𝑣 = (2 − 5𝑥)
•
𝑑𝑢
𝑑𝑥
= 0
𝑑𝑣
𝑑𝑥
= −5
•
𝑑𝑦
𝑑𝑥
=
𝑑
𝑢
𝑣
𝑑𝑥
=
v 𝑑𝑢
𝑑𝑥
− u 𝑑𝑣
𝑑𝑥
𝑣2
• =
(2−5𝑥)(0)−3(−5)
(2−5𝑥)2
=
0 + 15
(2 − 5𝑥)2
=
15
(2−5𝑥)2
• Y=1+
1
1+
1
𝑥
• Y=1+
1
1
1
+
1
𝑥
=1+
1
𝑥+1
𝑥
=1+
𝑥
𝑥+1
=
1
1
+
𝑥
𝑥+1
=
𝑥+1+𝑥
𝑥+1
=
2𝑥+1
𝑥+1
• NOW 𝑦 =
2𝑥+1
𝑥+1
• 𝑢 = 2𝑥 + 1 𝑣 =
•
𝑑𝑢
𝑑𝑥
= 2
𝑑𝑣
𝑑𝑥
= 1
•
𝑑𝑦
𝑑𝑥
=
𝑑
𝑢
𝑣
𝑑𝑥
=
v 𝑑𝑢
𝑑𝑥
− u 𝑑𝑣
𝑑𝑥
𝑣2 =
𝑥+1 2 −(2𝑥+1)(1)
(𝑥+1)2 =
2𝑥+2−2𝑥−1
(𝑥+1)2 =
1
(𝑥+1)2
Find derivative of
3
(𝑥+2)(𝑥+3)
• 𝑦 =
3
(𝑥+2)(𝑥+3)
• 𝑦 =
3
𝑥2+3𝑥+2𝑥+6
• ∴ 𝑦=
3
𝑥2+5𝑥+6
• NOW 𝑦 =
3
𝑥2+5𝑥+6
• 𝑢 = 3 𝑣 = 𝑥2
+ 5𝑥 + 6
•
𝑑𝑢
𝑑𝑥
= 0
𝑑𝑣
𝑑𝑥
= 2𝑥 + 5
•
𝒅𝒚
𝒅𝒙
=
𝒅
𝒖
𝒗
𝒅𝒙
=
v 𝒅𝒖
𝒅𝒙
− u 𝒅𝒗
𝒅𝒙
𝒗𝟐
• =
(𝑥2+5𝑥+6)(0)−𝟑(𝟐𝒙+𝟓)
(𝑥2+5𝑥+6)𝟐
• =
−𝟑(𝟐𝒙+𝟓)
(𝑥2+5𝑥+6)𝟐
• OR
• =
−𝟔𝒙−𝟏𝟓
(𝑥2+5𝑥+6)𝟐
(Find derivative of 𝑥 +
2𝑥+3
𝑥+2
𝑥 +
4𝑥+10
𝑥+3
• 𝑦 = 𝑥 +
2𝑥+3
𝑥+2
𝑥 +
4𝑥+10
𝑥+3
• 𝑦 =
𝑥
1
+
2𝑥+3
𝑥+2
𝑥
1
+
4𝑥+10
𝑥+3
• 𝑦 =
𝑥 𝑥+2 + 2𝑥+3
𝑥+2
𝑥 𝑥+3 + 4𝑥+10
𝑥+3
• 𝑦 =
𝑥2+2𝑥+2𝑥+3
𝑥+2
𝑥23𝑥+4𝑥+10
𝑥+3
• 𝑦 =
𝑥2+4𝑥+3
𝑥+2
𝑥2+7𝑥+10
𝑥+3
• 𝑦 =
𝑥2+3𝑥+𝑥+3
𝑥+2
𝑥2+5𝑥+2𝑥+10
𝑥+3
• 𝑦 =
𝑥 𝑥+3 +1(𝑥+3)
𝑥+2
𝑥 𝑥+5 +2(𝑥+5)
(𝑥+3)
• 𝑦 =
𝑥+1 𝑥+3
𝑥+2
𝑥+5 𝑥+2
𝑥+3
= 𝑥 + 1 𝑥 + 5
• 𝑦 = 𝑥 + 1 𝑥 + 5
• 𝑦 = 𝑥 𝑥 + 5 + 1 𝑥 + 5
• 𝑦 = 𝑥2 + 5𝑥 + 𝑥 + 5
• 𝑦 = 𝑥2
+ 6𝑥 + 5
• NOW
•
𝑑𝑦
𝑑𝑥
=
𝑑 (𝑥2+6𝑥+5)
𝑑𝑥
•
𝑑𝑦
𝑑𝑥
= 2𝑥 + 6
Find
𝑑𝑦
𝑑𝑥
if 𝑥 + 1 𝑦 + 1 = 18
• 𝑥 + 1 𝑦 + 1 = 18
• 𝑦 + 1 =
18
𝑥+1
• 𝑦 =
18
𝑥+1
− 1
• 𝑦 =
18−1 𝑥+1
𝑥+1
• 𝑦 =
18−𝑥−1
𝑥+1
• 𝑦=
17−𝑥
𝑥+1
• Now 𝑦 =
17−𝑥
𝑥+1
• LET 𝑢 = 17 − 𝑥 𝑣 = 𝑥 + 1
•
𝑑𝑢
𝑑𝑥
= −1
𝑑𝑣
𝑑𝑥
= 1
•
𝑑𝑦
𝑑𝑥
=
𝑑
𝑢
𝑣
𝑑𝑥
=
v 𝑑𝑢
𝑑𝑥
− u 𝑑𝑣
𝑑𝑥
𝑣2
•
𝑑𝑦
𝑑𝑥
=
𝑥+1 −1 −(17−𝑥)(1)
𝑥+1 2
•
𝑑𝑦
𝑑𝑥
=
−𝑥−1−17+𝑥
𝑥+1 2
• =
−18
𝑥+1 2
F𝑖𝑛𝑑
𝑑𝑦
𝑑𝑥
𝑖𝑓 𝑥𝑦 + 𝑥 + 𝑦 − 2 = 0
• 𝑥𝑦 + 𝑥 + 𝑦 − 2 = 0
• 𝑥𝑦 + 𝑦 = 2 − 𝑥
• 𝑦 𝑥 + 1 = 2 − 𝑥
• 𝑦 =
2−𝑥
𝑥+1
• N𝑜𝑤 𝑦 =
2−𝑥
𝑥+1
• LET 𝑢 = 2 − 𝑥 𝑣 = 𝑥 + 1
•
𝑑𝑢
𝑑𝑥
= −1
𝑑𝑣
𝑑𝑥
= 1
•
𝑑𝑦
𝑑𝑥
=
𝑑
𝑢
𝑣
𝑑𝑥
=
v 𝑑𝑢
𝑑𝑥
− u 𝑑𝑣
𝑑𝑥
𝑣2
•
𝑑𝑦
𝑑𝑥
=
𝑥+1 −1 −(2−𝑥)(1)
𝑥+1 2
• =
−𝑥−1−2+𝑥
𝑥+1 2
• =
−3
𝑥+1 2
𝐴𝑝𝑝𝑙𝑖𝑐𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑑𝑒𝑟𝑖𝑣𝑎𝑡𝑖𝑣𝑒𝑠
• If y = 𝑥𝑛 then
𝑑𝑦
𝑑𝑥
=n𝑥𝑛−1
• If y = x then
𝑑𝑦
𝑑𝑥
= 1
• If y=c then
𝑑𝑦
𝑑𝑥
=0
• If y=𝑒𝑥 then
𝑑𝑦
𝑑𝑥
= 𝑒𝑥
• If y= 𝑎𝑥
then
𝑑𝑦
𝑑𝑥
= 𝑎𝑥
loge
a
• 𝐼𝑓𝑦 =loge x then
𝑑𝑦
𝑑𝑥
=
1
𝑥
• 𝐹𝑖𝑛𝑑 𝑑𝑒𝑟𝑖𝑣𝑎𝑡𝑖𝑣𝑒 𝑜𝑓 𝑥3
𝑒𝑥
𝑤𝑖𝑡ℎ 𝑟𝑒𝑠𝑝𝑒𝑐𝑡 𝑡𝑜 𝑥
𝐻𝑒𝑟𝑒 𝑦 = 𝑥3
𝑒𝑥
𝑢 = 𝑥2 𝑣 = 𝑒𝑥

𝑑𝑢
𝑑𝑥
= 2𝑥
𝑑𝑣
𝑑𝑥
= 𝑒𝑥

𝑑𝑦
𝑑𝑥
= 𝑣
𝑑𝑢
𝑑𝑥
+ 𝑢
𝑑𝑣
𝑑𝑥
= (𝑒𝑥)(2𝑥)+(𝑥2)(𝑒𝑥)
= 𝑥𝑒𝑥(2 + 𝑥)
𝐴𝑝𝑝𝑙𝑖𝑐𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑑𝑒𝑟𝑖𝑣𝑎𝑡𝑖𝑣𝑒𝑠
• If y = 𝑥𝑛 then
𝑑𝑦
𝑑𝑥
=n𝑥𝑛−1
• If y = x then
𝑑𝑦
𝑑𝑥
= 1
• If y=c then
𝑑𝑦
𝑑𝑥
=0
• If y=𝑒𝑥 then
𝑑𝑦
𝑑𝑥
= 𝑒𝑥
• If y= 𝑎𝑥
then
𝑑𝑦
𝑑𝑥
= 𝑎𝑥
loge a
• 𝐼𝑓𝑦 =loge x then
𝑑𝑦
𝑑𝑥
=
1
𝑥
• 𝑓𝑖𝑛𝑑 𝑑𝑒𝑟𝑖𝑣𝑎𝑡𝑖𝑣𝑒 𝑜𝑓
𝑥4
log 𝑥
• 𝐻𝑒𝑟𝑒 𝑦 =
𝑥4
log 𝑥
• 𝑢 = 𝑥4
𝑣 = 𝑙𝑜𝑔𝑥
•
𝑑𝑢
𝑑𝑥
= 4𝑥3 𝑑𝑣
𝑑𝑥
=
1
𝑥
•
𝑑𝑦
𝑑𝑥
=
𝑑
𝑢
𝑣
𝑑𝑥
=
v 𝑑𝑢
𝑑𝑥
− u 𝑑𝑣
𝑑𝑥
𝑣2
=
𝑙𝑜𝑔𝑥 4𝑥3 − 𝑥4 1
𝑥
𝑙𝑜𝑔𝑥 2 =
𝑙𝑜𝑔𝑥 4𝑥3 − 𝑥3
𝑙𝑜𝑔𝑥 2
=
𝑥3 4𝑙𝑜𝑔𝑥−1
𝑙𝑜𝑔𝑥 2
𝐴𝑝𝑝𝑙𝑖𝑐𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑑𝑒𝑟𝑖𝑣𝑎𝑡𝑖𝑣𝑒𝑠
• If y = 𝑥𝑛 then
𝑑𝑦
𝑑𝑥
=n𝑥𝑛−1
• If y = x then
𝑑𝑦
𝑑𝑥
= 1
• If y=c then
𝑑𝑦
𝑑𝑥
=0
• If y=𝑒𝑥 then
𝑑𝑦
𝑑𝑥
= 𝑒𝑥
• If y= 𝑎𝑥
then
𝑑𝑦
𝑑𝑥
= 𝑎𝑥
loge a
• 𝐼𝑓𝑦 =loge x then
𝑑𝑦
𝑑𝑥
=
1
𝑥
• 𝐹𝑖𝑛𝑑 𝑑𝑒𝑟𝑖𝑣𝑎𝑡𝑖𝑣𝑒 𝑜𝑓 𝑥3/2 4𝑥
• 𝑢 = 𝑥3/2
𝑣 = 4𝑥
•
𝑑𝑢
𝑑𝑥
=
3
2
𝑥
3
2
−1
=
3
2
𝑥
1
2
𝑑𝑣
𝑑𝑥
= 4𝑥
log 4
•
𝑑
𝑢
𝑣
𝑑𝑥
=
v 𝑑𝑢
𝑑𝑥
− u 𝑑𝑣
𝑑𝑥
𝑣2
=
𝑙𝑜𝑔𝑥 4𝑥3 − 𝑥4 1
𝑥
𝑙𝑜𝑔𝑥 2 =
𝑙𝑜𝑔𝑥 4𝑥3 − 𝑥3
𝑙𝑜𝑔𝑥 2
=
𝑥3 4𝑙𝑜𝑔𝑥−1
𝑙𝑜𝑔𝑥 2
𝐴𝑝𝑝𝑙𝑖𝑐𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑑𝑒𝑟𝑖𝑣𝑎𝑡𝑖𝑣𝑒𝑠
• If y = 𝑥𝑛 then
𝑑𝑦
𝑑𝑥
=n𝑥𝑛−1
• If y = x then
𝑑𝑦
𝑑𝑥
= 1
• If y=c then
𝑑𝑦
𝑑𝑥
=0
• If y=𝑒𝑥 then
𝑑𝑦
𝑑𝑥
= 𝑒𝑥
• If y= 𝑎𝑥
then
𝑑𝑦
𝑑𝑥
= 𝑎𝑥
loge
a
• 𝐼𝑓𝑦 =loge x then
𝑑𝑦
𝑑𝑥
=
1
𝑥

derivatives part 1.pptx

  • 1.
  • 2.
    USING DEFINITION OBTAINDERIVATIVE • Find derivative of y = 𝒙 Here f(x)= 𝒙 Therefore f(x+h)= 𝒙 + 𝒉 Now according to definition of derivative • f’(x)= 𝐥𝐢𝐦 𝒉→𝟎 𝒇 𝒙+𝒉 −𝒇(𝒙) 𝒉 • = 𝐥𝐢𝐦 𝒉→𝟎 𝒙+𝒉− 𝒙 𝒉 • = 𝐥𝐢𝐦 𝒉→𝟎 𝒙+𝒉− 𝒙 𝒉 × 𝒙+𝒉+ 𝒙 𝒙+𝒉+ 𝒙 • = 𝐥𝐢𝐦 𝒉→𝟎 𝒙+𝒉 𝟐 − 𝒙 𝟐 𝒉( 𝒙+𝒉+ 𝒙) = lim ℎ→0 𝑥+ℎ−𝑥 ℎ ( 𝑥+ℎ+ 𝑥) = lim ℎ→0 ℎ ℎ ( 𝑥+ℎ+ 𝑥) = lim ℎ→0 1 ( 𝑥 + ℎ + 𝑥) = 1 ( 𝑥+0+ 𝑥) = 1 ( 𝑥 + 𝑥) = 1 2 𝑥
  • 3.
    DERIVATIVE OF CONSTANT( C ) • Find derivative of y =c Here f(x)=c Therefore f(x+h)=c Now according to definition of derivative • f’(x)= 𝐥𝐢𝐦 𝒉→𝟎 𝒇 𝒙+𝒉 −𝒇(𝒙) 𝒉 • = 𝐥𝐢𝐦 𝒉→𝟎 𝒄−𝒄 𝒉 • = 𝐥𝐢𝐦 𝒉→𝟎 𝟎 𝒉 • =0
  • 4.
    Using definition findderivatives • Find derivative y=3𝑥2 − 2 Here f(x)= 3𝑥2 − 2 Therefore f(x+h)= 3 𝑥 + ℎ 2 − 2 =3(𝒙𝟐 +2xh+𝒉𝟐 )-2 = 3𝒙𝟐 +6xh+3𝒉𝟐 -2 Now according to definition of derivative • f’(x)= 𝐥𝐢𝐦 𝒉→𝟎 𝒇 𝒙+𝒉 −𝒇(𝒙) 𝒉 =𝐥𝐢𝐦 𝒉→𝟎 3𝒙𝟐+6xh+3𝒉𝟐−2 −(3𝑥2 −2) 𝒉 =𝐥𝐢𝐦 𝒉→𝟎 3𝒙𝟐+6xh+3𝒉𝟐−2−3𝑥2+𝟐 𝒉 • =𝐥𝐢𝐦 𝒉→𝟎 6xh+3𝒉𝟐 𝒉 • = 𝐥𝐢𝐦 𝒉→𝟎 𝒉(6x+3𝒉) 𝒉 • = 𝐥𝐢𝐦 𝒉→𝟎 (𝟔𝒙 + 𝒉) • = 𝟔𝒙 + 𝟎 • = 𝟔𝒙
  • 5.
    Using definition findderivatives • Find derivative y=4𝑥2 + 5x − 2 Here f(x)= 4𝑥2 + 5x − 2 Therefore f(x+h)= 4 𝑥 + ℎ 2 + 5(x + h) − 2 =4(𝒙𝟐 +2xh+𝒉𝟐 ) + 𝟓(𝐱 + 𝐡)-2 = 4𝒙𝟐 +8xh+4𝒉𝟐 +5x+5h-2 Now according to definition of derivative • f’(x)= 𝐥𝐢𝐦 𝒉→𝟎 𝒇 𝒙+𝒉 −𝒇(𝒙) 𝒉 =𝐥𝐢𝐦 𝒉→𝟎 (4𝒙𝟐+8xh+4𝒉𝟐+5x+5h−2)−(4𝑥2+5x−2) 𝒉 =𝐥𝐢𝐦 𝒉→𝟎 4𝒙𝟐+8xh+4𝒉𝟐+5x+5h−2−4𝑥2−5x+2 𝒉 • =𝐥𝐢𝐦 𝒉→𝟎 8xh+4𝒉𝟐+5h 𝒉 • = 𝐥𝐢𝐦 𝒉→𝟎 𝒉(8x+4h+5) 𝒉 • = 𝐥𝐢𝐦 𝒉→𝟎 (8x+4h+5) • = 8𝒙 + 𝟒(𝟎) + 𝟓 • = 8𝒙+5
  • 6.
    IMPORTANT FORMULAE FOR DIFFERENTIATION •If y = 𝑥𝑛 then 𝑑𝑦 𝑑𝑥 =n𝑥𝑛−1 • If y = x then 𝑑𝑦 𝑑𝑥 = 1 • If y=c then 𝑑𝑦 𝑑𝑥 =0 • If y=𝑒𝑥 then 𝑑𝑦 𝑑𝑥 = 𝑒𝑥 • If y= 𝑎𝑥 then 𝑑𝑦 𝑑𝑥 = 𝑎𝑥 loge a • If y= loge x then 𝑑𝑦 𝑑𝑥 = 1 𝑥
  • 7.
    RULES OF DERIVATIVES •If U and V are functions of x then y=u+v then 𝑑𝑦 𝑑𝑥 = 𝑑(𝑢+𝑣) 𝑑𝑥 = 𝑑𝑢 𝑑𝑥 + 𝑑𝑣 𝑑𝑥 y=u−v then 𝑑𝑦 𝑑𝑥 = 𝑑(𝑢−𝑣) 𝑑𝑥 = 𝑑𝑢 𝑑𝑥 - 𝑑𝑣 𝑑𝑥 y=u×v then 𝑑𝑦 𝑑𝑥 = 𝑑(𝑢𝑣) 𝑑𝑥 = 𝑣 𝑑𝑢 𝑑𝑥 + u 𝑑𝑣 𝑑𝑥 Y=uvw then 𝑑𝑦 𝑑𝑥 = 𝑑(𝑢𝑣𝑤) 𝑑𝑥 = 𝑣𝑤 𝑑𝑢 𝑑𝑥 + 𝑢𝑤 𝑑𝑣 𝑑𝑥 + 𝑢𝑣 𝑑𝑤 𝑑𝑥 Y= 𝑢 𝑣 then 𝑑𝑦 𝑑𝑥 = 𝑑 𝑢 𝑣 𝑑𝑥 = v 𝑑𝑢 𝑑𝑥 − u 𝑑𝑣 𝑑𝑥 𝑣2 Chain rule : If y is function of u and u is function of x then 𝑑𝑦 𝑑𝑥 = 𝑑𝑦 𝑑𝑢 × 𝑑𝑢 𝑑𝑥
  • 8.
    If U andV are functions of x then (I)y=u+v then 𝑑𝑦 𝑑𝑥 = 𝑑(𝑢+𝑣) 𝑑𝑥 = 𝑑𝑢 𝑑𝑥 + 𝑑𝑣 𝑑𝑥 (II)y=u−v then 𝑑𝑦 𝑑𝑥 = 𝑑(𝑢−𝑣) 𝑑𝑥 = 𝑑𝑢 𝑑𝑥 - 𝑑𝑣 𝑑𝑥 Find 𝑑𝑦 𝑑𝑥 of the following functions using rule (i) and (ii) (I) 3𝑥2 +2 SOLUTION : I. Y= 3𝑥2 +2 𝑑𝑦 𝑑𝑥 = 𝑑3𝑥2 𝑑𝑥 + 𝑑2 𝑑𝑥 [∵ RULE (I) APPLIED ] = 3(2X)+0 =6X (ii)4𝑥2 +5X+1 SOLUTION : Y= 4𝑥2 +5X+1 𝑑𝑦 𝑑𝑥 = 𝑑4𝑥2 𝑑𝑥 + 𝑑5𝑥 𝑑𝑥 + 𝑑1 𝑑𝑥 = 4(2X)+5(1) +0 = 8X+5 (III) 5X-9 SOLUTION : Y=5X-9 𝑑𝑦 𝑑𝑥 = 𝑑 5x 𝑑𝑥 - 𝑑9 𝑑𝑥 =5(1)-0 =5
  • 9.
    Solve the following (i)y=𝑥3 + 𝑥2 + 𝑥 − 2 (II) y=7𝑥7 + 5𝑥4 − 20𝑥 + 37 • SOLUTION : • y=𝑥3 + 𝑥2 + 𝑥 − 2 • 𝑑𝑦 𝑑𝑥 = 𝑑𝑥3 𝑑𝑥 + 𝑑 𝑥2 𝑑𝑥 + 𝑑𝑥 𝑑𝑥 - 𝑑2 𝑑𝑥 • =(3𝑥3−1 ) +(2𝑥)+1-0 • = 3 𝑥2 +2𝑥+1 • SOLUTION: • y= 7𝑥7 + 5𝑥4 − 20𝑥 + 37 • 𝑑𝑦 𝑑𝑥 = 𝑑7𝑥7 𝑑𝑥 + 𝑑 5𝑥4 𝑑𝑥 - 𝑑20𝑥 𝑑𝑥 + 𝑑37 𝑑𝑥 • =7(7𝑥7−1 ) +5(4𝑥4−1 )- 20+0 • = 49𝑥6 +20𝑥3 − 20
  • 10.
    (I) y=u×v then 𝑑𝑦 𝑑𝑥 = 𝑑(𝑢𝑣) 𝑑𝑥 =𝑣 𝑑𝑢 𝑑𝑥 + u 𝑑𝑣 𝑑𝑥 II Y=uvw then 𝑑𝑦 𝑑𝑥 = 𝑑(𝑢𝑣𝑤) 𝑑𝑥 = 𝑣𝑤 𝑑𝑢 𝑑𝑥 + 𝑢𝑤 𝑑𝑣 𝑑𝑥 + 𝑢𝑣 𝑑𝑤 𝑑𝑥 • Find the derivative w.r.t 𝑥 • Y= (3𝑥2 − 2)(𝑥2 + 7) • 𝑢 = 3𝑥2 − 2 𝑣 = (𝑥2 + 7) • 𝑑𝑢 𝑑𝑥 =6𝑥 𝑑𝑣 𝑑𝑥 =2𝑥 • 𝑑𝑦 𝑑𝑥 = 𝑣 𝑑𝑢 𝑑𝑥 + u 𝑑𝑣 𝑑𝑥 • =(𝑥2 + 7)(6𝑥) + 3𝑥2 − 2 (2𝑥) • =(6𝑥3+42𝑥) +(6𝑥3-4𝑥) • = 6𝑥3 +42𝑥+ 6𝑥3 -4𝑥 • = 12𝑥3 +38𝑥 • Find the derivative w.r.t 𝑥 • Y= (2𝑥2 + 3)(3𝑥2 + 2)(𝑥+7) • 𝑢 = (2𝑥2 + 3) 𝑣 = 3𝑥2 + 2 𝑤 = (𝑥+7) • 𝑑𝑢 𝑑𝑥 = 4𝑥 + 0 𝑑𝑣 𝑑𝑥 = 6𝑥 + 0 𝑑𝑤 𝑑𝑥 = 1+0 • 𝑑𝑦 𝑑𝑥 = 𝑣𝑤 𝑑𝑢 𝑑𝑥 + 𝑢𝑤 𝑑𝑣 𝑑𝑥 + 𝑢𝑣 𝑑𝑤 𝑑𝑥 =(3𝑥2 + 2)(𝑥+7) 4𝑥+ (2𝑥2 + 3) (𝑥+7) 6𝑥+ (2𝑥2 + 3)(3𝑥2 + 2)1 = (3𝑥2 + 2)(4𝑥2+28𝑥)+ (2𝑥2 + 3)(6𝑥2+42𝑥) +(2𝑥2 + 3)(3𝑥2 + 2) = 4𝑥2 (3𝑥2 + 2)+ 28𝑥 (3𝑥2 + 2)+ 6𝑥2 (2𝑥2 + 3)+42𝑥(2𝑥2 + 3)+ 3𝑥2 (2𝑥2 + 3) + 2(2𝑥2 + 3) =12𝑥4 + 8𝑥2 + 84𝑥3 + 56𝑥 + 12𝑥4 + 18𝑥2 + 84𝑥3 + 126𝑥 + 6𝑥4 +9𝑥2 +4𝑥2 + 6 = 12𝑥4 + 12𝑥4 + 6𝑥4 +84𝑥3 +84𝑥3 + 8𝑥2 +18𝑥2 +9𝑥2 +4𝑥2 +56𝑥 + 126𝑥+6 =30𝑥4 + 168𝑥3 + 39𝑥2 + 182𝑥 + 6
  • 11.
    NOW TRY YOURSELF • FIND DERIVATIVES WITH RESPECT TO 𝑥 • Y=(2𝑥 + 3) 5𝑥3 − 2 • Y=𝑥4 + 𝑥5 + 5𝑥6 + 3𝑥2 + 3𝑥3 − 9 • Y=3𝑥4 + 13𝑥3 − 9𝑥 + 15 • Y=(𝑥 + 1)(9𝑥 + 5)(𝑥2 − 9) • Y= 3𝑥2 + 5𝑥 − 9 • Y=(𝑥2 + 𝑥 − 1)(𝑥2 + 𝑥 + 1) • Y=(2X-1)(6X+1) • Y=7𝑥2 + 123𝑥 − 100
  • 12.
    Y= 𝑢 𝑣 then 𝑑𝑦 𝑑𝑥 = 𝑑 𝑢 𝑣 𝑑𝑥 = v 𝑑𝑢 𝑑𝑥 − u𝑑𝑣 𝑑𝑥 𝑣2 • FIND THE DERIVATIVE OF 𝑦 = 1+𝑥 1+𝑥2 • HERE 𝑦 = 1+𝑥 1+𝑥2 = 𝑢 𝑣 • LET 𝑢 = (1 + 𝑥) 𝑣 = (1 + 𝑥2) • 𝑑𝑢 𝑑𝑥 = 0 + 1 𝑑𝑣 𝑑𝑥 = 0 + 2𝑥 • 𝑑𝑦 𝑑𝑥 = 𝑑 𝑢 𝑣 𝑑𝑥 = v 𝑑𝑢 𝑑𝑥 − u 𝑑𝑣 𝑑𝑥 𝑣2 • = (1+𝑥2) (1)−(1+𝑥)(2x) (1+𝑥2)2 = 1 + 𝑥2 − 2𝑥 − 2𝑥2 (1 + 𝑥2)2 = 1−2𝑥−𝑥2 (1+𝑥2)2 • FIND DERIVATIVE 𝑦 = 𝑥2+𝑥+1 𝑥2−𝑥+1 • HERE 𝑦 = 𝑥2+𝑥+1 𝑥2−𝑥+1 = 𝑢 𝑣 • LET 𝑢 = (𝑥2 + 𝑥 + 1) 𝑣 = (𝑥2 − 𝑥 + 1) • 𝑑𝑢 𝑑𝑥 = 2𝑥 + 1 𝑑𝑣 𝑑𝑥 = 2𝑥 − 1 • 𝑑𝑦 𝑑𝑥 = 𝑑 𝑢 𝑣 𝑑𝑥 = v 𝑑𝑢 𝑑𝑥 − u 𝑑𝑣 𝑑𝑥 𝑣2 • = (𝑥2−𝑥+1) (2X+1)−(𝑥2+𝑥+1)(2x−1) (1−𝑥+𝑥2)2 = =
  • 13.
    Find derivati𝑣𝑒𝑠 w.r.t.𝑥 • Y= 3 2−5𝑥 • HERE 𝑦 = 3 2−5𝑥 = 𝑢 𝑣 • LET 𝑢 = 3 𝑣 = (2 − 5𝑥) • 𝑑𝑢 𝑑𝑥 = 0 𝑑𝑣 𝑑𝑥 = −5 • 𝑑𝑦 𝑑𝑥 = 𝑑 𝑢 𝑣 𝑑𝑥 = v 𝑑𝑢 𝑑𝑥 − u 𝑑𝑣 𝑑𝑥 𝑣2 • = (2−5𝑥)(0)−3(−5) (2−5𝑥)2 = 0 + 15 (2 − 5𝑥)2 = 15 (2−5𝑥)2 • Y=1+ 1 1+ 1 𝑥 • Y=1+ 1 1 1 + 1 𝑥 =1+ 1 𝑥+1 𝑥 =1+ 𝑥 𝑥+1 = 1 1 + 𝑥 𝑥+1 = 𝑥+1+𝑥 𝑥+1 = 2𝑥+1 𝑥+1 • NOW 𝑦 = 2𝑥+1 𝑥+1 • 𝑢 = 2𝑥 + 1 𝑣 = • 𝑑𝑢 𝑑𝑥 = 2 𝑑𝑣 𝑑𝑥 = 1 • 𝑑𝑦 𝑑𝑥 = 𝑑 𝑢 𝑣 𝑑𝑥 = v 𝑑𝑢 𝑑𝑥 − u 𝑑𝑣 𝑑𝑥 𝑣2 = 𝑥+1 2 −(2𝑥+1)(1) (𝑥+1)2 = 2𝑥+2−2𝑥−1 (𝑥+1)2 = 1 (𝑥+1)2
  • 14.
    Find derivative of 3 (𝑥+2)(𝑥+3) •𝑦 = 3 (𝑥+2)(𝑥+3) • 𝑦 = 3 𝑥2+3𝑥+2𝑥+6 • ∴ 𝑦= 3 𝑥2+5𝑥+6 • NOW 𝑦 = 3 𝑥2+5𝑥+6 • 𝑢 = 3 𝑣 = 𝑥2 + 5𝑥 + 6 • 𝑑𝑢 𝑑𝑥 = 0 𝑑𝑣 𝑑𝑥 = 2𝑥 + 5 • 𝒅𝒚 𝒅𝒙 = 𝒅 𝒖 𝒗 𝒅𝒙 = v 𝒅𝒖 𝒅𝒙 − u 𝒅𝒗 𝒅𝒙 𝒗𝟐 • = (𝑥2+5𝑥+6)(0)−𝟑(𝟐𝒙+𝟓) (𝑥2+5𝑥+6)𝟐 • = −𝟑(𝟐𝒙+𝟓) (𝑥2+5𝑥+6)𝟐 • OR • = −𝟔𝒙−𝟏𝟓 (𝑥2+5𝑥+6)𝟐
  • 15.
    (Find derivative of𝑥 + 2𝑥+3 𝑥+2 𝑥 + 4𝑥+10 𝑥+3 • 𝑦 = 𝑥 + 2𝑥+3 𝑥+2 𝑥 + 4𝑥+10 𝑥+3 • 𝑦 = 𝑥 1 + 2𝑥+3 𝑥+2 𝑥 1 + 4𝑥+10 𝑥+3 • 𝑦 = 𝑥 𝑥+2 + 2𝑥+3 𝑥+2 𝑥 𝑥+3 + 4𝑥+10 𝑥+3 • 𝑦 = 𝑥2+2𝑥+2𝑥+3 𝑥+2 𝑥23𝑥+4𝑥+10 𝑥+3 • 𝑦 = 𝑥2+4𝑥+3 𝑥+2 𝑥2+7𝑥+10 𝑥+3 • 𝑦 = 𝑥2+3𝑥+𝑥+3 𝑥+2 𝑥2+5𝑥+2𝑥+10 𝑥+3 • 𝑦 = 𝑥 𝑥+3 +1(𝑥+3) 𝑥+2 𝑥 𝑥+5 +2(𝑥+5) (𝑥+3) • 𝑦 = 𝑥+1 𝑥+3 𝑥+2 𝑥+5 𝑥+2 𝑥+3 = 𝑥 + 1 𝑥 + 5 • 𝑦 = 𝑥 + 1 𝑥 + 5 • 𝑦 = 𝑥 𝑥 + 5 + 1 𝑥 + 5 • 𝑦 = 𝑥2 + 5𝑥 + 𝑥 + 5 • 𝑦 = 𝑥2 + 6𝑥 + 5 • NOW • 𝑑𝑦 𝑑𝑥 = 𝑑 (𝑥2+6𝑥+5) 𝑑𝑥 • 𝑑𝑦 𝑑𝑥 = 2𝑥 + 6
  • 16.
    Find 𝑑𝑦 𝑑𝑥 if 𝑥 +1 𝑦 + 1 = 18 • 𝑥 + 1 𝑦 + 1 = 18 • 𝑦 + 1 = 18 𝑥+1 • 𝑦 = 18 𝑥+1 − 1 • 𝑦 = 18−1 𝑥+1 𝑥+1 • 𝑦 = 18−𝑥−1 𝑥+1 • 𝑦= 17−𝑥 𝑥+1 • Now 𝑦 = 17−𝑥 𝑥+1 • LET 𝑢 = 17 − 𝑥 𝑣 = 𝑥 + 1 • 𝑑𝑢 𝑑𝑥 = −1 𝑑𝑣 𝑑𝑥 = 1 • 𝑑𝑦 𝑑𝑥 = 𝑑 𝑢 𝑣 𝑑𝑥 = v 𝑑𝑢 𝑑𝑥 − u 𝑑𝑣 𝑑𝑥 𝑣2 • 𝑑𝑦 𝑑𝑥 = 𝑥+1 −1 −(17−𝑥)(1) 𝑥+1 2 • 𝑑𝑦 𝑑𝑥 = −𝑥−1−17+𝑥 𝑥+1 2 • = −18 𝑥+1 2
  • 17.
    F𝑖𝑛𝑑 𝑑𝑦 𝑑𝑥 𝑖𝑓 𝑥𝑦 +𝑥 + 𝑦 − 2 = 0 • 𝑥𝑦 + 𝑥 + 𝑦 − 2 = 0 • 𝑥𝑦 + 𝑦 = 2 − 𝑥 • 𝑦 𝑥 + 1 = 2 − 𝑥 • 𝑦 = 2−𝑥 𝑥+1 • N𝑜𝑤 𝑦 = 2−𝑥 𝑥+1 • LET 𝑢 = 2 − 𝑥 𝑣 = 𝑥 + 1 • 𝑑𝑢 𝑑𝑥 = −1 𝑑𝑣 𝑑𝑥 = 1 • 𝑑𝑦 𝑑𝑥 = 𝑑 𝑢 𝑣 𝑑𝑥 = v 𝑑𝑢 𝑑𝑥 − u 𝑑𝑣 𝑑𝑥 𝑣2 • 𝑑𝑦 𝑑𝑥 = 𝑥+1 −1 −(2−𝑥)(1) 𝑥+1 2 • = −𝑥−1−2+𝑥 𝑥+1 2 • = −3 𝑥+1 2
  • 18.
    𝐴𝑝𝑝𝑙𝑖𝑐𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑𝑑𝑒𝑟𝑖𝑣𝑎𝑡𝑖𝑣𝑒𝑠 • If y = 𝑥𝑛 then 𝑑𝑦 𝑑𝑥 =n𝑥𝑛−1 • If y = x then 𝑑𝑦 𝑑𝑥 = 1 • If y=c then 𝑑𝑦 𝑑𝑥 =0 • If y=𝑒𝑥 then 𝑑𝑦 𝑑𝑥 = 𝑒𝑥 • If y= 𝑎𝑥 then 𝑑𝑦 𝑑𝑥 = 𝑎𝑥 loge a • 𝐼𝑓𝑦 =loge x then 𝑑𝑦 𝑑𝑥 = 1 𝑥 • 𝐹𝑖𝑛𝑑 𝑑𝑒𝑟𝑖𝑣𝑎𝑡𝑖𝑣𝑒 𝑜𝑓 𝑥3 𝑒𝑥 𝑤𝑖𝑡ℎ 𝑟𝑒𝑠𝑝𝑒𝑐𝑡 𝑡𝑜 𝑥 𝐻𝑒𝑟𝑒 𝑦 = 𝑥3 𝑒𝑥 𝑢 = 𝑥2 𝑣 = 𝑒𝑥  𝑑𝑢 𝑑𝑥 = 2𝑥 𝑑𝑣 𝑑𝑥 = 𝑒𝑥  𝑑𝑦 𝑑𝑥 = 𝑣 𝑑𝑢 𝑑𝑥 + 𝑢 𝑑𝑣 𝑑𝑥 = (𝑒𝑥)(2𝑥)+(𝑥2)(𝑒𝑥) = 𝑥𝑒𝑥(2 + 𝑥)
  • 19.
    𝐴𝑝𝑝𝑙𝑖𝑐𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑𝑑𝑒𝑟𝑖𝑣𝑎𝑡𝑖𝑣𝑒𝑠 • If y = 𝑥𝑛 then 𝑑𝑦 𝑑𝑥 =n𝑥𝑛−1 • If y = x then 𝑑𝑦 𝑑𝑥 = 1 • If y=c then 𝑑𝑦 𝑑𝑥 =0 • If y=𝑒𝑥 then 𝑑𝑦 𝑑𝑥 = 𝑒𝑥 • If y= 𝑎𝑥 then 𝑑𝑦 𝑑𝑥 = 𝑎𝑥 loge a • 𝐼𝑓𝑦 =loge x then 𝑑𝑦 𝑑𝑥 = 1 𝑥 • 𝑓𝑖𝑛𝑑 𝑑𝑒𝑟𝑖𝑣𝑎𝑡𝑖𝑣𝑒 𝑜𝑓 𝑥4 log 𝑥 • 𝐻𝑒𝑟𝑒 𝑦 = 𝑥4 log 𝑥 • 𝑢 = 𝑥4 𝑣 = 𝑙𝑜𝑔𝑥 • 𝑑𝑢 𝑑𝑥 = 4𝑥3 𝑑𝑣 𝑑𝑥 = 1 𝑥 • 𝑑𝑦 𝑑𝑥 = 𝑑 𝑢 𝑣 𝑑𝑥 = v 𝑑𝑢 𝑑𝑥 − u 𝑑𝑣 𝑑𝑥 𝑣2 = 𝑙𝑜𝑔𝑥 4𝑥3 − 𝑥4 1 𝑥 𝑙𝑜𝑔𝑥 2 = 𝑙𝑜𝑔𝑥 4𝑥3 − 𝑥3 𝑙𝑜𝑔𝑥 2 = 𝑥3 4𝑙𝑜𝑔𝑥−1 𝑙𝑜𝑔𝑥 2
  • 20.
    𝐴𝑝𝑝𝑙𝑖𝑐𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑𝑑𝑒𝑟𝑖𝑣𝑎𝑡𝑖𝑣𝑒𝑠 • If y = 𝑥𝑛 then 𝑑𝑦 𝑑𝑥 =n𝑥𝑛−1 • If y = x then 𝑑𝑦 𝑑𝑥 = 1 • If y=c then 𝑑𝑦 𝑑𝑥 =0 • If y=𝑒𝑥 then 𝑑𝑦 𝑑𝑥 = 𝑒𝑥 • If y= 𝑎𝑥 then 𝑑𝑦 𝑑𝑥 = 𝑎𝑥 loge a • 𝐼𝑓𝑦 =loge x then 𝑑𝑦 𝑑𝑥 = 1 𝑥 • 𝐹𝑖𝑛𝑑 𝑑𝑒𝑟𝑖𝑣𝑎𝑡𝑖𝑣𝑒 𝑜𝑓 𝑥3/2 4𝑥 • 𝑢 = 𝑥3/2 𝑣 = 4𝑥 • 𝑑𝑢 𝑑𝑥 = 3 2 𝑥 3 2 −1 = 3 2 𝑥 1 2 𝑑𝑣 𝑑𝑥 = 4𝑥 log 4 • 𝑑 𝑢 𝑣 𝑑𝑥 = v 𝑑𝑢 𝑑𝑥 − u 𝑑𝑣 𝑑𝑥 𝑣2 = 𝑙𝑜𝑔𝑥 4𝑥3 − 𝑥4 1 𝑥 𝑙𝑜𝑔𝑥 2 = 𝑙𝑜𝑔𝑥 4𝑥3 − 𝑥3 𝑙𝑜𝑔𝑥 2 = 𝑥3 4𝑙𝑜𝑔𝑥−1 𝑙𝑜𝑔𝑥 2
  • 21.
    𝐴𝑝𝑝𝑙𝑖𝑐𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑𝑑𝑒𝑟𝑖𝑣𝑎𝑡𝑖𝑣𝑒𝑠 • If y = 𝑥𝑛 then 𝑑𝑦 𝑑𝑥 =n𝑥𝑛−1 • If y = x then 𝑑𝑦 𝑑𝑥 = 1 • If y=c then 𝑑𝑦 𝑑𝑥 =0 • If y=𝑒𝑥 then 𝑑𝑦 𝑑𝑥 = 𝑒𝑥 • If y= 𝑎𝑥 then 𝑑𝑦 𝑑𝑥 = 𝑎𝑥 loge a • 𝐼𝑓𝑦 =loge x then 𝑑𝑦 𝑑𝑥 = 1 𝑥