## anonymous one year ago The value of y varies directly with x2, and y = 64 when x = 4. What is the value of y when x = 6?

1. anonymous

if that x2 stands for $$x^2$$, then: $y=Ax^2$ where $$A$$ is some constant, if you plug $$y=64$$ for $$x=4$$ you can find the value of $$A$$ and then plug $$x=6$$ and see what you get for $$y$$...

2. anonymous

6^2 would make it 36 right?

3. anonymous

@Greg_D

4. anonymous

that woul be the case $$A=1$$... you can et the value for $$A$$ from: $64=A\times 4^2$ find that and then calculate $$y=A\times 6^2$$

5. anonymous

what is a

6. anonymous

the problem says: "The value of y varies directly with x^2, and y = 64 when x = 4" so y must equal "something" times x^2, i called that something A

7. anonymous

im sorry im the worst XD

8. anonymous

576

9. anonymous

no problem, just keep asking until you understand ! what did you get for A ?

10. anonymous

well 64/4 is 16 so i multiplied 36 by 16 to get 576

11. anonymous

note that $$A=\frac{64}{4^2}$$ dont forget the square!

12. anonymous

oh yeah

13. anonymous

i dont remember how to do that

14. anonymous

well $$4^2=16$$ so $$A=\frac{64}{16}=4$$

15. anonymous

so 4 times 36 ?

16. anonymous

for 144?

17. anonymous

:) that is what i get... good work!