CPM Homework Help : CCA Problem 11-21

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11-21.

Solve the equations and inequalities below by completing the square.

$x^2-2x-3\le0$
Hint (a):
Solve this like an equation and then test points to find the solution region(s).
More Help (a):
The perfect square form is $\left(x+1\right)^2=4$ .
Answer (a):
$-1\le x\le3$

$x^2+4x=3$
Answer (b):
$x=-2\pm\sqrt{7}$

$x^2+12x+39>0$
Hint (c):
Refer to part (a).
More Help (c):
The perfect square form is $\left(x+6\right)^2>-3$

$x^2-3x-13.75=0$

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