If x varies directly as a square of y for y=6, x=72. Find x for y=9.

Question

Belinda Solomon · Accepted Answer

Solution:Since x varies directly as a square of y.

∴ x = k y^{2}

, where k is any constant.
Substitute y=6, x=72 in above relation.

\Rightarrow 72 = k \cdot 6^{2} \Rightarrow k = \frac{72}{36} ∴ k = 2

Therefore, the above expression becomes

x = 2 y^{2}

.
We have to find x for y=9.

\Rightarrow x = 2 \times 9^{2} \Rightarrow x = 2 \times 81 ∴ x = 162

Thus, the value of x is 162.

If x varies directly as a square of y for y=6, x=72. Find x for...