Solve: -x^4 + 200 = 102x^2

Answer 1

-x^4-102x²+200=0

X=x²
-X²-102X+200=0
try to solve this equation and then u can solve -x^4-102x²+200=0

Answer 2

-x^4-102x^2+200=0
(-x^2)^2-102(x^2)+200=0

I'm stuck at this point