Question

How do you solve `x^4-81`?

Answer 1

Resolve by factorization
`(x+3)(x-3)(x^2+9)`

Explanation:

Resolve by factorization considering `a^2 - b^2 = (a+b)(a-b)`
Detail is below
`x^4-3^4 = (x^2)^2-(3^2)^2=(x^2-3^2)(x^2+3^2)=(x+3)(x-3)(x^2+9)`