add 14 both sides
2x^2+12x=14
make term in front of x^2 1
divide both sid s by 2
x^2+6x=7
take 1/2 of 6 and square it and add to both sides (6/2=3 3^2=9)
x^2+6x+9=7+9
factor pefect square
(x+3)^2=16
sqrt both sides
x+3=+/-4
minus 3
x=+/-4-3
x=4-3 or -4-3
x=1 or -7