REVIEW: 
How does the graph of a direct 
variation 
look like? 
The graph is a straight 
line.
How does the graph of a direct square 
variation 
look like? 
The graph is a curve line called parabola.
Read the ff. equations correctly. 
1.) x = ky 
2.) d = kf 
3.) kw = j 
4.) k = m 
Direct Variation Direct Square Variation 
n 
5.) ky = z 
1.) A = kd2 
2.) R = kp2 
3.) k = s 
q2 
4.) kg2 = h 
5.) n = k 
t2
Think of some real-life situations 
wherein as one variable increases, the 
other variable decreases or vice-versa. 
Examples: 
• As the number of trees decreases, 
air pollution increases. 
• As the speed of a car increases, 
the length of travel time decreases.
Consider a rectangle whose area is 36 cm2. If the 
width(w) is 2 cm, then its length(l) is 18 cm. What happens 
when the width is increased to 3 cm? 4 cm? 
width(w) 2 3 4 5 
length(l) 18 
Area(A) 36 36 36 36 
12 9 7.2 
The graph is neither a straight line nor a parabola 
but a half of a two-part curve known as 
hyperbola.
Lesson III: 
Inverse Variation 
Whenever the product of corresponding values of 
two quantities is a constant, then one quantity varies 
inversely as the other. 
In symbols, 
y = k(1) or y = k k = xy 
x x 
This means that y is inversely proportional to x, or x 
is inversely proportional to y.
Examples: 
A.For a given gas of constant temperature, the pressure(P) varies 
inversely as the volume(V). If P = 6 when V = 24, 
find P when V = 36. 
P = k 
V 
k =PV 6 ? 
= (6)(24) 24 36 
= 144 
= 144 = 4 
36 
B. Find the number of days 10 workers can complete a job if 5 
workers can complete the same job in 7 days. 
d = k 
w 
k =dw 
= (7)(5) 
= 35 
= 35 = 3.5 
10 
5 10 
7 ?
Read the equations below correctly. 
I = k_ 
R 
V = 
k_ 
P 
k = df 
P = k_ gt = k 
h
GROUP ACTIVITY: 
Answer the following. 
1.If y varies inversely as x, and y = 48 
when x = 10, find y when x = 32 
2. In the relation P1V1 = P2V2, P1 = 1.5 and 
V1 = 24. Find V2 when P2 = 2. 
3. For a given distance, the required 
time(t) varies inversely as the rate R. If 
t = 6 when R= 45 find R when t = 4 ½. 
y = 15 
V2 = 18 
R = 60
QUIZ III 
Write the ff. in equation form where k represent 
the constant of variation. 
1.The time(t) required to travel a given fixed distance is 
inversely proportional to the speed(r). 
2.The altitude(h) of a triangle with constant area varies 
inversely as its base(b). 
3.The temperature(T) at which water boils varies 
inversely as the number of feet(h) above sea level. 
Answer the following. 
4.If c varies inversely as d and c = 30 when d = 9, find d 
when c = 540. 
5.The gravitational force(f) between two bodies varies 
inversely as the square of distance(d) between them. Find 
f when d = 5 and f = 100 when d = 4. 
t = k 
r 
h = k 
b 
T = k 
h 
d = 1 
2
Have a nice day…………. 
GOD 
BLESS 
YOU!!!

Inverse Variation

  • 1.
    REVIEW: How doesthe graph of a direct variation look like? The graph is a straight line.
  • 2.
    How does thegraph of a direct square variation look like? The graph is a curve line called parabola.
  • 3.
    Read the ff.equations correctly. 1.) x = ky 2.) d = kf 3.) kw = j 4.) k = m Direct Variation Direct Square Variation n 5.) ky = z 1.) A = kd2 2.) R = kp2 3.) k = s q2 4.) kg2 = h 5.) n = k t2
  • 4.
    Think of somereal-life situations wherein as one variable increases, the other variable decreases or vice-versa. Examples: • As the number of trees decreases, air pollution increases. • As the speed of a car increases, the length of travel time decreases.
  • 5.
    Consider a rectanglewhose area is 36 cm2. If the width(w) is 2 cm, then its length(l) is 18 cm. What happens when the width is increased to 3 cm? 4 cm? width(w) 2 3 4 5 length(l) 18 Area(A) 36 36 36 36 12 9 7.2 The graph is neither a straight line nor a parabola but a half of a two-part curve known as hyperbola.
  • 6.
    Lesson III: InverseVariation Whenever the product of corresponding values of two quantities is a constant, then one quantity varies inversely as the other. In symbols, y = k(1) or y = k k = xy x x This means that y is inversely proportional to x, or x is inversely proportional to y.
  • 7.
    Examples: A.For agiven gas of constant temperature, the pressure(P) varies inversely as the volume(V). If P = 6 when V = 24, find P when V = 36. P = k V k =PV 6 ? = (6)(24) 24 36 = 144 = 144 = 4 36 B. Find the number of days 10 workers can complete a job if 5 workers can complete the same job in 7 days. d = k w k =dw = (7)(5) = 35 = 35 = 3.5 10 5 10 7 ?
  • 8.
    Read the equationsbelow correctly. I = k_ R V = k_ P k = df P = k_ gt = k h
  • 9.
    GROUP ACTIVITY: Answerthe following. 1.If y varies inversely as x, and y = 48 when x = 10, find y when x = 32 2. In the relation P1V1 = P2V2, P1 = 1.5 and V1 = 24. Find V2 when P2 = 2. 3. For a given distance, the required time(t) varies inversely as the rate R. If t = 6 when R= 45 find R when t = 4 ½. y = 15 V2 = 18 R = 60
  • 10.
    QUIZ III Writethe ff. in equation form where k represent the constant of variation. 1.The time(t) required to travel a given fixed distance is inversely proportional to the speed(r). 2.The altitude(h) of a triangle with constant area varies inversely as its base(b). 3.The temperature(T) at which water boils varies inversely as the number of feet(h) above sea level. Answer the following. 4.If c varies inversely as d and c = 30 when d = 9, find d when c = 540. 5.The gravitational force(f) between two bodies varies inversely as the square of distance(d) between them. Find f when d = 5 and f = 100 when d = 4. t = k r h = k b T = k h d = 1 2
  • 11.
    Have a niceday…………. GOD BLESS YOU!!!