Solve. x^2−5x−8=0

Enter the answers as exact values

x=_______or x=__________

Thanks much!

Guest Oct 22, 2018

#1**+1 **

x^2 - 5x - 8 = 0 add 8 to both sides

x^2 - 5x = 8

Take 1/2 of 5 = 5/2....square it = 25/4 .....add to both sides

x^2 - 5x + 25/4 = 8 + 25/4 factor the left side, simpliify the right

(x - 5/2)^2 = 57/4 take both roots

x - 5/2 = ± √ [ 57 / 4 ]

x - 5/2 = ± √57 / 2 add 5/2 to both sides

x = 5/2 + √57/ 2 or x = 5/2 - √57 / 2

CPhill Oct 22, 2018