The document provides formulas and concepts for mathematics including: 1) Formulas for quadratic equations such as the general form, quadratic formula, and forming a quadratic equation from its roots. 2) Properties of quadratic functions including their shapes based on the value of a and completing the square to find minimum/maximum values. 3) Concepts for coordinate geometry including calculating the distance and gradient between points, properties of parallel and perpendicular lines, and formulas for the midpoint and area of a triangle.

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Add Maths Formulae List: Form 4 (Update 18/9/08)
01 Functions
Absolute Value Function Inverse Function
If y = f ( x ) , then f −1 ( y ) = x
f ( x ), if f ( x ) ≥ 0
f ( x) Remember:
− f ( x), if f ( x ) < 0 Object = the value of x
Image = the value of y or f(x)
f(x) map onto itself means f(x) = x
02 Quadratic Equations
General Form Quadratic Formula
ax 2 + bx + c = 0
−b ± b 2 − 4ac
where a, b, and c are constants and a ≠ 0. x=
2a
*Note that the highest power of an unknown of a
quadratic equation is 2. When the equation can not be factorized.
Forming Quadratic Equation From its Roots: Nature of Roots
If α and β are the roots of a quadratic equation
b c
α +β =− αβ = b 2 − 4ac >0 ⇔ two real and different roots
a a
b 2 − 4ac =0 ⇔ two real and equal roots
The Quadratic Equation b 2 − 4ac <0 ⇔ no real roots
x 2 − (α + β ) x + αβ = 0 b 2 − 4ac ≥0 ⇔ the roots are real
or
x − ( SoR ) x + ( PoR ) = 0
2
SoR = Sum of Roots
PoR = Product of Roots
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03 Quadratic Functions
General Form Completing the square:
f ( x) = ax 2 + bx + c f ( x) = a ( x + p)2 + q
where a, b, and c are constants and a ≠ 0. (i) the value of x, x = − p
(ii) min./max. value = q
*Note that the highest power of an unknown of a (iii) min./max. point = (− p, q)
quadratic function is 2. (iv) equation of axis of symmetry, x = − p
Alternative method:
a > 0 ⇒ minimum ⇒ ∪ (smiling face)
f ( x) = ax 2 + bx + c
a < 0 ⇒ maximum ⇒ ∩ (sad face)
b
(i) the value of x, x = −
2a
b
(ii) min./max. value = f (− )
2a
b
(iii) equation of axis of symmetry, x = −
2a
Quadratic Inequalities Nature of Roots
a > 0 and f ( x) > 0 a > 0 and f ( x) < 0
b 2 − 4ac > 0 ⇔ intersects two different points
at x-axis
a b a b b − 4ac = 0 ⇔ touch one point at x-axis
2
b 2 − 4ac < 0 ⇔ does not meet x-axis
x < a or x > b a< x<b
04 Simultaneous Equations
To find the intersection point ⇒ solves simultaneous equation.
Remember: substitute linear equation into non- linear equation.
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05 Indices and Logarithm
Fundamental if Indices Laws of Indices
Zero Index, a0 = 1 a m × a n = a m+n
1
Negative Index, a −1 =
a a m ÷ a n = a m−n
a
( ) −1 =
b ( a m ) n = a m× n
b a
1 ( ab) n = a n b n
Fractional Index an = a n
m a n an
an = a n m
( ) = n
b b
Fundamental of Logarithm Law of Logarithm
log a y = x ⇔ a x = y log a mn = log a m + log a n
log a a = 1 log a
m
= log a m − log a n
n
log a a x = x
log a mn = n log a m
log a 1 = 0
Changing the Base
log c b
log a b =
log c a
1
log a b =
logb a
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06 Coordinate Geometry
Distance and Gradient
Distance Between Point A and C =
(x1 − x2 )2 + (x1 − x2 )2
y2 − y1
Gradient of line AC, m =
x2 − x1
Or
⎛ y − int ercept ⎞
Gradient of a line, m = − ⎜ ⎟
⎝ x − int ercept ⎠
Parallel Lines Perpendicular Lines
When 2 lines are parallel, When 2 lines are perpendicular to each other,
m1 = m2 . m1 × m2 = −1
m1 = gradient of line 1
m2 = gradient of line 2
Midpoint A point dividing a segment of a line
⎛ x1 + x2 y1 + y2 ⎞ A point dividing a segment of a line
Midpoint, M = ⎜ , ⎟ ⎛ nx + mx2 ny1 + my2 ⎞
⎝ 2 2 ⎠ P =⎜ 1 , ⎟
⎝ m+n m+n ⎠
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Area of triangle:
Area of Triangle
1
=
2
1
A=
2
( x1 y2 + x2 y3 + x3 y1 ) − ( x2 y1 + x3 y2 + x1 y3 )
Form of Equation of Straight Line
General form Gradient form Intercept form
ax + by + c = 0 y = mx + c x y
+ =1
a b
m = gradient
c = y-intercept b
a = x-intercept m=−
b = y-intercept a
Equation of Straight Line
Gradient (m) and 1 point (x1, y1) 2 points, (x1, y1) and (x2, y2) given x-intercept and y-intercept given
given
y − y1 = m( x − x1 ) y − y1 y2 − y1 x y
= + =1
x − x1 x2 − x1 a b
Equation of perpendicular bisector ⇒ gets midpoint and gradient of perpendicular line.
Information in a rhombus:
A B
(i) same length ⇒ AB = BC = CD = AD
(ii) parallel lines ⇒ mAB = mCD or mAD = mBC
(iii) diagonals (perpendicular) ⇒ mAC × mBD = −1
(iv) share same midpoint ⇒ midpoint AC = midpoint
D BD
C (v) any point ⇒ solve the simultaneous equations
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Remember:
y-intercept ⇒ x = 0
cut y-axis ⇒ x = 0
x-intercept ⇒ y = 0
cut x-axis ⇒ y = 0
**point lies on the line ⇒ satisfy the equation ⇒ substitute the value of x and of y of the point into the
equation.
Equation of Locus
( use the formula of The equation of the locus of a The equation of the locus of a moving
distance) moving point P ( x, y ) which is point P ( x, y ) which is always
The equation of the locus of a always at a constant distance equidistant from two fixed points A and B
moving point P ( x, y ) which from two fixed points is the perpendicular bisector of the
is always at a constant A ( x1 , y1 ) and B ( x2 , y 2 ) with straight line AB.
distance (r) from a fixed point a ratio m : n is
A ( x1 , y1 ) is PA = PB
PA m ( x − x1 ) + ( y − y1 ) 2 = ( x − x2 ) 2 + ( y − y2 ) 2
2
=
PA = r PB n
( x − x1 ) 2 + ( y − y1 ) 2 = r 2 ( x − x1 ) 2 + ( y − y1 ) 2 m 2
=
( x − x2 ) + ( y − y 2 ) 2 n 2
More Formulae and Equation List:
SPM Form 4 Physics - Formulae List
SPM Form 5 Physics - Formulae List
SPM Form 4 Chemistry - List of Chemical Reactions
SPM Form 5 Chemistry - List of Chemical Reactions
All at
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07 Statistics
Measure of Central Tendency
Grouped Data
Ungrouped Data
Without Class Interval With Class Interval
Mean
Σx Σ fx Σ fx
x= x= x=
N Σf Σf
x = mean x = mean x = mean
Σx = sum of x Σx = sum of x f = frequency
x = value of the data f = frequency x = class mark
N = total number of the x = value of the data
data (lower limit+upper limit)
=
2
Median
m = TN +1 m = TN +1 ⎛ 1N −F⎞
2 2 m = L+ ⎜ 2
⎜ f ⎟C
⎟
When N is an odd number. When N is an odd number. ⎝ m ⎠
m = median
TN + TN TN + T N L = Lower boundary of median class
+1 +1
m= 2 2
m= 2 2 N = Number of data
2 2 F = Total frequency before median class
When N is an even When N is an even number. fm = Total frequency in median class
number. c = Size class
= (Upper boundary – lower boundary)
Measure of Dispersion
Grouped Data
Ungrouped Data
Without Class Interval With Class Interval
variance
σ =2∑ x2 −x
2
σ =
2 ∑ fx 2 −x
2
σ =
2 ∑ fx 2 −x
2
N ∑f ∑f
σ = variance σ = variance σ = variance
Σ(x − x )
2
Σ(x − x )
2
Standard Σ f (x − x)
2
σ= σ=
Deviation N N σ=
Σf
Σx 2 Σx 2
σ= − x2 σ= − x2 Σ fx 2
N N σ= − x2
Σf
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The variance is a measure of the mean for the square of the deviations from the mean.
The standard deviation refers to the square root for the variance.
Effects of data changes on Measures of Central Tendency and Measures of dispersion
Data are changed uniformly with
+k −k ×k ÷k
Measures of Mean, median, mode +k −k ×k ÷k
Central Tendency
Range , Interquartile Range No changes ×k ÷k
Measures of
Standard Deviation No changes ×k ÷k
dispersion
Variance No changes × k2 ÷ k2
08 Circular Measures
Terminology
Convert degree to radian:
Convert radian to degree:
π
xo = ( x × )radians
180 180
×
π 180
x radians = ( x × ) degrees
π
radians degrees
π
×
180
Remember:
180 = π rad 1.2 rad
O
??? 0.7 rad ???
360 = 2π rad
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Length and Area
r = radius
A = area
s = arc length
θ = angle
l = length of chord
Arc Length: Length of chord: Area of Sector: Area of Triangle: Area of Segment:
s = rθ θ 1 2 1 2 1 2
l = 2r sin A= rθ A= r sin θ A= r (θ − sin θ )
2 2 2 2
09 Differentiation
Differentiation of a Function I
Gradient of a tangent of a line (curve or
straight) y = xn
dy δy dy
= lim ( ) = nx n−1
dx δ x →0 δ x dx
Example
y = x3
Differentiation of Algebraic Function
dy
Differentiation of a Constant = 3x 2
dx
y=a a is a constant
dy
=0 Differentiation of a Function II
dx
y = ax
Example dy
y=2 = ax1−1 = ax 0 = a
dx
dy
=0
dx Example
y = 3x
dy
=3
dx
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Differentiation of a Function III Chain Rule
y = ax n y = un u and v are functions in x
dy dy dy du
= anx n−1 = ×
dx dx du dx
Example Example
y = 2 x3 y = (2 x 2 + 3)5
dy du
= 2(3) x 2 = 6 x 2 u = 2 x 2 + 3, therefore = 4x
dx dx
dy
y = u5 , therefore = 5u 4
du
Differentiation of a Fractional Function
dy dy du
= ×
1 dx du dx
y=
xn = 5u 4 × 4 x
Rewrite = 5(2 x 2 + 3) 4 × 4 x = 20 x(2 x 2 + 3) 4
y = x−n
dy −n Or differentiate directly
= − nx − n−1 = n+1 y = (ax + b) n
dx x
dy
= n.a.(ax + b) n −1
Example dx
1
y=
x y = (2 x 2 + 3)5
y = x −1 dy
= 5(2 x 2 + 3) 4 × 4 x = 20 x(2 x 2 + 3) 4
dy −1 dx
= −1x −2 = 2
dx x
Law of Differentiation
Sum and Difference Rule
y =u±v u and v are functions in x
dy du dv
= ±
dx dx dx
Example
y = 2 x3 + 5 x 2
dy
= 2(3) x 2 + 5(2) x = 6 x 2 + 10 x
dx
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Product Rule Quotient Rule
y = uv u and v are functions in x u
y= u and v are functions in x
dy du dv v
= v +u
dx dx dx du dv
v −u
dy dx dx
=
Example dx v2
y = (2 x + 3)(3 x 3 − 2 x 2 − x)
Example
u = 2x + 3 v = 3x3 − 2 x 2 − x
x2
du dv y=
=2 = 9 x2 − 4 x − 1 2x +1
dx dx
u = x2 v = 2x +1
dy du dv
=v +u du dv
dx dx dx = 2x =2
dx dx
=(3 x − 2 x − x)(2) + (2 x + 3)(9 x 2 − 4 x − 1)
3 2
du dv
v −u
dy
= dx 2 dx
Or differentiate directly dx v
y = (2 x + 3)(3x3 − 2 x 2 − x) dy (2 x + 1)(2 x) − x 2 (2)
=
dy dx (2 x + 1) 2
= (3x3 − 2 x 2 − x)(2) + (2 x + 3)(9 x 2 − 4 x − 1)
dx 4 x2 + 2 x − 2 x2 2 x2 + 2 x
= =
(2 x + 1) 2 (2 x + 1) 2
Or differentiate directly
x2
y=
2x +1
dy (2 x + 1)(2 x) − x 2 (2)
=
dx (2 x + 1) 2
4 x2 + 2 x − 2 x2 2 x2 + 2 x
= =
(2 x + 1) 2 (2 x + 1) 2
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Gradients of tangents, Equation of tangent and Normal
Gradient of tangent at A(x1, y1):
dy
= gradient of tangent
dx
Equation of tangent: y − y1 = m( x − x1 )
Gradient of normal at A(x1, y1):
1
mnormal = −
mtangent
If A(x1, y1) is a point on a line y = f(x), the gradient 1
of the line (for a straight line) or the gradient of the = gradient of normal
− dy
dy dx
tangent of the line (for a curve) is the value of
dx Equation of normal : y − y1 = m( x − x1 )
when x = x1.
Maximum and Minimum Point
dy
Turning point ⇒ =0
dx
At maximum point, At minimum point ,
2
dy d y dy d2y
=0 <0 =0 >0
dx dx 2 dx dx 2
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Rates of Change Small Changes and Approximation
Small Change:
dA dA dr
Chain rule = ×
dt dr dt δ y dy dy
≈ ⇒ δ y ≈ ×δ x
δ x dx dx
dx
If x changes at the rate of 5 cms -1 ⇒
=5 Approximation:
dt
Decreases/leaks/reduces ⇒ NEGATIVES values!!! ynew = yoriginal + δ y
dy
= yoriginal + ×δ x
dx
δ x = small changes in x
δ y = small changes in y
If x becomes smaller ⇒ δ x = NEGATIVE
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10 Solution of Triangle
Sine Rule: Cosine Rule: Area of triangle:
a
a b c a2 = b2 + c2 – 2bc cosA
= = b2 = a2 + c2 – 2ac cosB
sin A sin B sin C C
c2 = a2 + b2 – 2ab cosC
b
Use, when given
2 sides and 1 non included b2 + c2 − a 2
cos A =
angle 2bc 1
2 angles and 1 side A= a b sin C
2
Use, when given
2 sides and 1 included angle C is the included angle of sides a
a a B 3 sides and b.
A
A a a c
b 180 – (A+B)
A
b b
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Case of AMBIGUITY If ∠C, the length AC and length AB remain unchanged,
the point B can also be at point B′ where ∠ABC = acute
A
and ∠A B′ C = obtuse.
If ∠ABC = θ, thus ∠AB′C = 180 – θ .
180 - θ
θ Remember : sinθ = sin (180° – θ)
C B′ B
Case 1: When a < b sin A Case 2: When a = b sin A
CB is too short to reach the side opposite to C. CB just touch the side opposite to C
Outcome: Outcome:
No solution 1 solution
Case 3: When a > b sin A but a < b. Case 4: When a > b sin A and a > b.
CB cuts the side opposite to C at 2 points CB cuts the side opposite to C at 1 points
Outcome: Outcome:
2 solution 1 solution
Useful information:
In a right angled triangle, you may use the following to solve the
c problems.
b (i) Phythagoras Theorem: c = a 2 + b2
θ
a Trigonometry ratio:
(ii)
sin θ = b , cos θ = a , tan θ =
c c
b
a
(iii) Area = ½ (base)(height)
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11 Index Number
Price Index Composite index
P Σ Wi I i
I = 1
× 100 I=
P0 Σ Wi
I = Price index / Index number I = Composite Index
P0 = Price at the base time W = Weightage
P1 = Price at a specific time
I = Price index
I A, B × I B ,C = I A,C ×100
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