How do you solve y^2 - 3y - 14 = 0y23y14=0 by completing the square?

1 Answer
May 10, 2015

(y-(3/2))^2 = y^2 - 3y + 9/4(y(32))2=y23y+94,
so y^2 - 3y - 14 = (y - 3/2)^2 - (14+9/4)y23y14=(y32)2(14+94)
= (y-3/2)^2 - 65/4=(y32)2654.

And, since we are given that y^2 - 3y - 14 =0y23y14=0

(y - 3/2)^2 = 65/4(y32)2=654

Hence y = +-sqrt(65/4)+3/2 = +-sqrt(65)/2+3/2y=±654+32=±652+32.