PLEASE SOLVE FOR X
x^4-5x^2+4=0

x = 4 and x = -4

x = 1 and x = -1

Step-by-step explanation:

let u = x^2

Then,

u^2-5u+4 = 0

(u - 4)(u - 1) = 0

u = 4 and u = 1

we substitute back for u

Then,

x^2 = 4

x = 4 and x = -4

x^2 = 1

x = 1 and x = -1

no because after the troops were pulled many blacks were killed by hangings lynchings and other cruel ways which in a way interrupted the reconstruction of the south and differed from the way abraham lincoln had an idea of reconstruction