If y is directly proportional to x² and y = 1/8 when x = ½, what is the positive value of x when y = 9/2?

Question

help please i have SATs in a couple months :S

Answer 1

y=kx^2

Therefore,

k=y/x^2=(1/8)/(1/4)=1/2

Therefore,

x^2=y/k=(9/2)/(1/2)=9

Therefore,

x=3.

Thanks.

Answer 2

If y is proportional to x² then we can write:

Cy=x²

substituting for x and y we have:

C(1/8)=(1/2)²

C=2

Now to find out what x is when y=9/2 you use C

2(9/2)=x²

9=x²

3=x

you win!

Answer 3

im really bad at all this stuff sry cant hlp