Question

Please Help I will fan and give medals!!!:)
Write the quadratic variation equation for the relationship:
y varies directly with x2 and y = 36 when x = 3.
A.y = 12x
B.y = ¼x2
C.y = 4x2
D.y = x2 + 25
@ranga

Answer 1

"y varies directly with x^2" implies
y = k * x^2 ---- (1)
When x = 3, y = 36
Plug the values into equation (1) and solve for k.

Answer 2

36=k*9

Answer 3

then I should divide each side bye 9?

Answer 4

Yes. Divide each side by 9 to solve for k.

Answer 5

so 4=k?

Answer 6

yes, k = 4. Put k in the equation y = k * x^2 and see which answer choice represents the equation.

Answer 7

Instead of writing x2, I prefer to write it as x^2 (meaning x raised to 2 to indicate that 2 is an exponent).

Answer 8

36=4*9

Answer 9

You solve for k and got k = 4.
Put just k = 4 in the equation y = k * x^2
y = 4x^2 is the equation we are after.
Which answer choice has y = 4x^2 (also written as y = 4x2)

Answer 10

oh duh c.:)

Answer 11

Yep! :)

Answer 12

Thanks again!

Answer 13

You are welcome.