How do you solve using the completing the square method 2x^2+7x-5=0?

1 Answer
Mar 3, 2018

color(blue)(x = (1/4) (3sqrt11 - 7), -(1/4)(3sqrt11 + 7)

Explanation:

2x2 + 7x - 5 = 0

Dividing by 2, x2 + 2 * (7/4) x = 5/2

Adding (7/4)^2 to both sides,

x^2 = (2*(7/4)x + (7/4)^2 = 5/2 + (7/4)^2 = 99/16

(x+7/4)^2 = (sqrt(99/16))^2

x + 7/4 = +- sqrt(99/16)

x = sqrt(99/16) - 7/4, -sqrt(99/16 ) - 7/4

x = (1/4) (3sqrt11 - 7), -(1/4)(3sqrt11 + 7)