Question

If the sum of the squares of roots of the equation $x^2+2x-P=0$ is $10$, then the value of $P$ will be

• A. $-3$
• B. $3$
• C. $6$
• D. $-6$

Answer 1

Answer: (B)

$3$

$x^2+2x-P=0$

Let roots be $\alpha$ and $\beta$

$\alpha +\beta =-2$

$\alpha \beta =-P$

${\alpha }^2+{\beta }^2=10$

$(\alpha +\beta {)}^2$=${\alpha }^2+{\beta }^2+2\alpha \beta$

${(\alpha +\beta )}^2-2\alpha \beta =10$

$4+2P=10$

$2P=6$

$P=3$