Question

Solve x2 – 2x = 8 by completing the square. Show your work for full credit.

Answer 1

\[x ^{2}-2x-8=0\]
(x+2)(x-4)=0
x+2=0 x-4=0
x=-2 & x=4

Answer 2

x2 – 2x +1 -1= 8
(x-1)2 -1 =8
(x-1)2 =9
x-1=+-3
x=4
x=-2

Answer 3

my way is what you looking for @dmartinez130. @katlg87 solved it by factorizing

Answer 4

\[x^{2}-2x=8\]
\[x^{2}-2x-8=0\]
\[x^{2}-4x+2x-8=0\]
x(x-4)+2(x-4)=0
(x+2) (x+4)
x=-2 OR x=4

Answer 5

rewrite the equation

\[x2 -2x = 8\]

the general form is

\[ax^2 + bx + c\]

to complete the square add \[(\frac{b}{2})^2\]

to both sides

in you question add (-2/2)^1 to both sides

\[x^2 -2x + 1 = 9\]

now factorise the left hand side

\[(x -1)^2 = 9 \]