Question

Solve:

$x^2+7x+12=0$

• A. $x=4,-3$
• B. $x=-4,-3$
• C. $x=4,4$
• D. $x=4,-2$

Answer 1

The correct option is B $x=-4,-3$

The given quadratic equation $x^2+7x+12=0$ can be solved by finding the factors of $12$ such that the addition or subtraction of two factors is equal to the coefficient of the middle term that is $4\times 3=12,4+3=7$

Therefore, we have:

$x^2+7x+12=0\Rightarrow x^2+4x+3x+12=0\Rightarrow x(x+4)+3(x+4)=0\Rightarrow (x+3)(x+4)=0\Rightarrow (x+3)=0,(x+4)=0\Rightarrow x=-3,x=-4$

Hence, $x=-4,-3$.