### Home > CCAA8 > Chapter 11 Unit 12 > Lesson CCA: 11.1.2 > Problem11-21

11-21.

Solve the equations and inequalities below by completing the square.

1.  $x^2−2x−3\le0$

Solve this like an equation and then test points to find the solution region(s).

The perfect square form is $(x+1)^2=4$.

$−1\le x\le3$

1.  $x^2+4x=3$

$x = -2 \pm \sqrt{7}$

1.  $x^2+12x+39>0$

Refer to part (a).

The perfect square form is $(x+6)^2>−3$

1.  $x^2−3x−13.75=0$