Question 162104
You made a mistake when you substracted 13 from both sides. You should have:

{{{x^2+14x+13=0}}}
{{{x^2+14x=-13}}}
*note the -13 term on the right
Divide coefficient of x by 2 and square it. Add this result to both sides:
{{{x^2+14x+49=49-13}}}
Re-write left side as a perfect square and simplify right side:
{{{(x+7)^2=36}}}
Take square root of both sides:
x+7= +/-6
Solve for x for boh the plus and minus case:
{{{highlight(x=-1)}}}
{{{highlight(x=-13)}}}
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Good Luck,
tutor_paul@yahoo.com