SOLUTION: Could you please help me? I am so lost on how to do these.... {{{x^2+7x=-12}}} I tried to do the part where you take half of b and got 3.5... then squared it to get 12.25 and p

Question 136350This question is from textbook Algebra 1
: Could you please help me? I am so lost on how to do these.... I tried to do the part where you take half of b and got 3.5... then squared it to get 12.25 and put it back in for c and got x^2+7x+12.25=-12+12.25 but i"m lost other than that. We're supposed to be "solving quadratic equations by completing the square" if it helps any. This question is from textbook Algebra 1

Answer by Edwin McCravy(20055) (Show Source): You can put this solution on YOUR website!
Could you please help me? I am so lost on how to do these.... I tried to do the part where you take half of b and got 3.5... then squared it to get 12.25 and put it back in for c and got x^2+7x+12.25=-12+12.25 but i"m lost other than that. We're supposed to be "solving quadratic equations by completing the square" if it helps any.

Multiply by , getting .
Now square .
Now add to both sides:

write the as

The LCD on the right is , so multiply by

Now factor the left side:

The left side is a perfect square (that's why the method is
called "completing the square"). So we write the left side
as a square, the square of a binomial:

Next we use the principle of square roots:
= �
= �
Now we solve for x by adding to both sides:
= �
= �
Using the +
= +
=

Using the -
=

Edwin
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