Chapter SH, Problem 9.20EP

To determine

To solve equation by completing the square.

Answer to Problem 9.20EP

  $x=2.1,-6.1$(rounded off to the nearest tenth)

Explanation of Solution

Given information :

The function provided is $x^2+4x-8=5$

Formula used :

To solve the equation by completing the square the $x^2$ and $x$ terms need to be isolated then the square is completed by adding the required constant to both sides of the equation.

Calculation :

  $x^2+4x-8=5$

The above expression can also be written as.

  $x^2+4x+4=5+8+4$

Completing the sqaure.

  ${(x+2)}^2=17$

Taking square root of both sides

  $x+2=\sqrt{17}$

Simplifying.

  $x=\pm 4.12-2$

Therefore, $x=2.12,-6.12$ .