SOLUTION: If y varies as directly as the square of x , and y =75/8 when x =5 ,find y when x =2

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Question 1155913: If y varies as directly as the square of x , and y =75/8 when x =5 ,find y when x =2
Found 3 solutions by Theo, MathTherapy, josgarithmetic:
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
the direct variation formula is y = kx
y = 75/8 when x = 5
formula becomes 75/8 = k * 5
divide both sides of this equation by 5 to get:
k = (75/8) / 5
solve for k to get:
k = 75/40 = 1.875
k is the constant of variation.
it stays the same regardless of the value of x, with y being dependent on both the value of k and the value of x.
when x = 2, the formula becomes y = 1.875 * 2
solve for y to get y = 3.75
when x = 2, y = 3.75
that's your solution.


Answer by MathTherapy(10551) About Me  (Show Source):
You can put this solution on YOUR website!
If y varies as directly as the square of x , and y =75/8 when x =5 ,find y when x =2

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
y varies as directly as the square of x ,y=kx%5E2


y =75/8 when x =5, 75%2F8=k%2A5%5E2
k=75%2F%288%2A25%29
k=3%2F8


The model equation is highlight_green%28y=%283%2F8%29x%5E2%29.


find y when x =2.
y=%283%2F8%29%2A2%5E2
y=3%2A4%2F%282%2A4%29
y=3%2F2, done.