Question

Y varies directly with the square of x. If y=40 when x=4, find y when x=7

Answer 1

y = 245/2

Explanation:

y = k x^2

Where k is the constant of variation

Let y= 40 and x=4

40 = k *(4)^2

40 = k*16

40/16 = k

5/2 = k

y =5/2 x^2

Let x=7

y = 5/2 (7)^2

y = 5/2(49)

y = 245/2