Algebra Question

Question

If y varies directly as the square of x, and y=12 when x=3, find y when x=6

Answer 1

If y varies directly as the square of x, then y = kx², for some constant, k.  

 

Since y = 12 when x = 3, we have 12 = k(3)².  So, k = 4/3.

 

Therefore, y = (4/3)x²

 

So, when x = 6, y = (4/3)(6)² = 48