how do you solve X⁴-35X²-36=0 and X⁴ + 16X² - 225 = 0

Question

It is a linear equation with exponents.The first one is raised to the power 4 and the second raised to the power 2.

Answer 1

x^4-35x^2-36=0=(x^2-36)(x^2+1)=(x-6)(x+6)(x^2+1), so (non-complex) solutions are x=6 and x=-6. The complex solutions would also include x=i and x=-i.

x^4+16x^2-225=0=(x^2+25)(x^2-9)=(x^2+25)(x-3)(x+3), so (non-complex) solutions are x=3 and x=-3. The complex solutions would also include x=5i and x=-5i.