Question

solve by completing the square: y^2+7y+12=0

Answer 1

FIrst subtract 12 from both sides, this leaves us with

y^2 + 7y = -12

Now add to both sides (7/2)^2 => 49/4, this leaves us with

y^2 + 7y + 49/4= -12 + 49/4

so now we have =,

(y + 7/2)^2 = 1/4

Take square root of both sides

y + 7/2 = 1/2

multiply both sides by 2

2y + 7 = 1

subtract 7 from both sides

2y = -6

divide both sides by 2

y = -3