Chapter 9 - Quadratic Functions and Equations - 9-5 Completing the Square - Lesson Check - Page 564: 4

$x = 7.5, -9$

$2z^2+3z=135$ $(2z^2+3z)/2=135/2$ $z^2+1.5z=67.5$ $z^2+1.5z+(1.5/2)^2=67.5+(1.5/2)^2$ $z^2+1.5z+.5625=67.5+.5625$ $(z+.75)^2 = 68.0625$ $\sqrt {x+.75}^2 = \sqrt {68.0625}$ $ x+.75 = 8.25$ or $x+.75 = -8.25$ $x = 7.5, -9$