Question

If the ratio of the roots of the equation $p{x}^2+qx+r=0$ is $a:b,$ then $\frac{ab}{(a+b{)}^2}=$

• (A) p²/qr
• (B) pr/q²
• (C) q²/pr
• (D) pq/r²

Answer 1

The Correct Option is B

Explanation:
Let roots are aα and bα ⇒ ( a + b ) α = -q/p$$\begin{array}{c}\frac{ab{\alpha }^2}{(a+b{)}^2{\alpha }^2}=\frac{r}{p}\cdot \frac{p^2}{q^2}\\ \frac{ab}{(a+b{)}^2}=\frac{rp}{q^2}\end{array}$$