Aya101
contestada

What equation results from completing the square and then factoring x^2+4x=12?

A) (x+2)^2=10
B) (x+2)^2=14
C) (x+2)^2=16
D) (x+2)^2=8

Respuesta :

x² + 4x =12
x² + 4x = 16 - 4
x² + 4x + 4 = 16
(x+2)² = 16

Answer: C.

Answer:

The correct answer is

option B : [tex](x+2)^2 = 16[/tex]

Step-by-step explanation:

Here the given quadratic equation is

[tex]x^2 +4x=12[/tex]

To complete the square we  add both sides square of half of coefficient of x

we have

coefficient of x = 4

half of coefficient of [tex]x=\frac{4}{2} =2[/tex]

square of half of coefficient of x = [tex]2^2 = 4[/tex]

So we add 4 to both sides

[tex]x^2 +4x+ 4=12+4[/tex]

[tex]x^2+4x+4 = 16[/tex]

we have formula [tex]a^2+2ab+b^2 =(a+b)^2[/tex]

so using this formula we can write

[tex]x^2+4x+4 = x^2+4x+2^2 = (x+2)^2[/tex]

hence we have

[tex](x+2)^2 = 16[/tex]