Question

Solve x- 8x = 20 by completing the square. Which is the solution set of the equation?

Answer 1

The right question is

$x ^{2} -8x=20$

now multiply 1/2 by the coefficient of x which is 8

$\frac{1}{2} \times 8=4$

now add square of 4 on both side of equation we will get

${x}^{2} -8x+ {4}^{2} =20+ {4}^{2}$

$(x-4)^2=20+16$

$(x-4)^2=36$

taking square root on both sides

we get

$(x-4)=-+6$

$x-4=6, x-4=-6$

$x=6+4 , x=-6+4$

$x=10,-2$

so third option is correct

if u find any confusion u can ask me

i hope you will understand it

Thank u