Question

Variable y varies directly with x2, and y = 196 when x = 7.

Answer 1

$y=kx^2$
k - a constant

$y=196 \ when \ x=7 \\ 196=k \times 7^2 \\ 196=49k \\ \frac{196}{49}=k \\ k=4 \\ \\ \boxed{y=4x^2}$