Question

y varies directly as the square of x. When x = 5, y = 100. Find y when x = 6.

y = 105

y = 120

y = 144

y = 150

Answer 1

@surdawi

Answer 2

y = k*x
100 = k * 5

can you calculate k?

Answer 3

@rebecca1233 wanna try it?

Answer 4

500

Answer 5

how?

Answer 6

100 *5 = 500

Answer 7

100 = k * 5
you need to divide

Answer 8

after you figure out k for direct variation with x (as practice)

you are ready to tackle the question
y varies directly as the square of x

\[ y= kx^2\]

Answer 9

It is the same idea. replace x with 5 and y with 100 in the equation
\[ y= kx^2\]
then "solve" for k. Can you do that?