Question 981399
x^2+14x+9=0
x^2+14x=-9
take half of the x term and square it, adding that number to both sides of the equation.

x^2+14x+49= -9+49
(x+7)^2=40
x+7= sqrt (40)=+/- 2 sqrt 10
x= -7 +/- 2 sqrt (10)