128+2x^4=40x^2 как решить?

Question

128+2x^4=40x^2 как решить?

Answer 1

X² = t ≥ 0

2t² - 40t + 128 = 0
t² - 20t + 64 = 0
D = 400 - 256 = 144
t1 = (20 - 12)/2 = 4
t2 = (20 + 12)/2 = 16

x1 = -2
x2 = 2
x3 = -4
x4 = 4

Answer 2

128+2x^4-40x^2=0|:2
x^4-20x^2+64=0
x1x2=64
x1+x2=20
x1=16
x2=4
или
Д1=10*10-64=100-64=36=6^2
х1=10+6=16
x2=10-6=4