Question

solve this problem plz
ans is -3/2​

Answer 1

First, expand the brackets.

Left hand side :

$(2x+1)(2x+6)=2x(2x+6)+1(2x+6)=4x^2+12x+2x+6\\=2x^2+14x+6$

$-7(x-2)=-7x+14$

$4x^2+14x+6-7x+14=4x^2+(14-7)x+14+6\\=4x^2+7x+20$

Right hand side :

$4(x+1)(x-1)=4\{x(x-1)+1(x-1)\}=4(x^2-x+x-1)\\=4x^2-4$

$4x^2-4-9x=4x^2-9x-4$

Last, solve the equation.

$4x^2+7x+20=4x^2-9x-4$

$4x^2+7x+20-(4x^2-9x-4)=0$

$(4-4)x^2+(7+9)x+20+4=0$

$16x+24=0$

∴ $x=-\frac{3}{2}$