Question

Solve the following quadratic equation by factorization method: $(2x+3{)}^2-81=0$

• A. $-6,3$
• B. $-6,2$
• C. $-3,3$
• D. None of these

Answer 1

The correct option is A $-6,3$

Given equation is $(2x+3{)}^2-81=0$

$\Rightarrow 4x^2+12x+9-81=0$ [ $(a+b{)}^2=a^2+2ab+b^2$ ]

$\Rightarrow 4x^2+12x-72=0$

$\Rightarrow x^2+3x-18=0$ [ Dividing equation by $4$ ]

$\Rightarrow x^2+6x-3x-18=0$

$\Rightarrow x(x+6)-3(x+6)=0$

$\Rightarrow (x+6)(x-3)=0$

$\Rightarrow x+6=0$ and $x-3=0$

$\therefore$ $x=-6$ and $x=3$

$\therefore$ $x=-6,3$