Question

Which of the following are solutions to the equation below?
Check all that apply.
x2 + 10x + 25 = 8

Answer 1

Answer:

The correct options for the solution values are:

• $x=2\sqrt{2}-5$

• $x=-2\sqrt{2}-5$

Step-by-step explanation:

Given the expression

$x^2+10x+25=8$

Subtract 25 from both sides

$x^2+10x+25-25=8-25$

Simplify

$x^2+10x=-17$

Add 25 or 5² to both sides

$x^2+10x+5^2=8$

as

$x^2+10x+5^2=\left(x+5\right)^2$

so the expression becomes

$\left(x+5\right)^2=8$

$\mathrm{For\:}f^2\left(x\right)=a\mathrm{\:the\:solutions\:are\:}f\left(x\right)=\sqrt{a},\:-\sqrt{a}$

solve

$x+5=\sqrt{8}$

Subtract 5 from both sides

$x+5-5=2\sqrt{2}-5$

$x=2\sqrt{2}-5$

solve

$x+5=-\sqrt{8}$

Subtract 5 from both sides

$x+5-5=-2\sqrt{2}-5$

$x=-2\sqrt{2}-5$

Therefore, the solution to the equation

$x=2\sqrt{2}-5,\:x=-2\sqrt{2}-5$

Hence, the correct options for the solution values are:

• $x=2\sqrt{2}-5$

• $x=-2\sqrt{2}-5$