CPM Homework Help : CCA2 Problem 4-70

Using the technique of completing the square, solve $x^2+12x+15=75\ \text{for}\ x$ .

Hint:

See the Math Notes box in Lesson 2.1.4 for help with completing the square. Also see problem 3-117.

Completed Square Form:

$(x+6)^2=96$

What steps were used to obtain this equation?

Now solve the equation.

Step 1:

Take the square root of both sides.

Step 2:

Subtract $6$ from both sides.

Step 3:

Simplify your answer.

More Help:

Since the original equation had an $x^2$ -term, you should try to find 2 solutions.