Xpangkat2 - 4pangkat2 - 5=0

[tex] {x}^{2} - 4x - 5 = 0 \\ (x - 5)(x + 1) = 0 \\ x = 5 \: \: \: atau \: x = - 1[/tex]

[tex] x^{2} [/tex] - [tex] 4^{2} [/tex] -5 = 0
[tex] x^{2} [/tex] - 16 - 5 = 0
[tex] x^{2} [/tex] -21 = 0
[tex] x^{2} [/tex] = 21
x                        = [tex] \sqrt{21} [/tex]