Direct and Inverse Variation

Direct or Inverse

1

The equation is y=k / x . Is this direct or inverse variation?

^{Inverse Variation}

3

The distance d a car travels varies directly with the time t. Is this direct or inverse variation?

Direct Variation

5

The cost C of mangoes varies directly with its weight w. Is this direct or inverse variation?

Direct Variation

Constant of Variation

1

Given y=-5x, what is the constant of variation

k = -5

3

If y varies directly with x and y=24 when x=8, what is the constant of variation?

k=3

5

If y varies inversely with x. When x=4, the corresponding value of y = -6.  

k=-24

Direct Variation

1

TRUE OR FALSE : The constant of variation in direct variation is found by multiplying x and y.

FALSE

3

If y varies directly with x and y=80 when x=16, find the equation of variation.

y=5x

5

The area A of a circle varies directly with the square of its radius r. If the area of a circle is 50 sq cm when the radius is 5 cm, what is the area when the radius is 8 cm?

A=2×64=128

Inverse Variation

1

TRUE OR FALSE : In inverse variation, the constant k changes as the values of x and y change.

FALSE 

3

If y varies inversely with x, and y=6 when x=3 what is the constant of variation?

k = 18

5

R varies inversely as T. If R=1500 when T=4 find R when T=10.

R=600