Question

If one root of the equation $x^2+7x+a=0$ is $-2$, then find the value of $a$.

• A. $-9$
• B. $10$
• C. $-10$
• D. $9$

Answer 1

The correct option is B $10$

If $x=-2$ is the root of the given quadratic equation, then

It will satisfy the equation.

Therefore, at $x=-2$, $(-2{)}^2+7(-2)+a=0$

Which gives us $a=10$