Question

What are the solutions of the equation x4 – 5x2 - 36 = 0? Use factoring to solve.

Answer 1

Answer:

x = -2i and x = 2i

x = 3 and x = - 3

Step-by-step explanation:

x^4 - 5x^2 - 36 = 0

let u = x^2 and substitute

we have:

u^2 - 5u - 36 = 0

(u - 9)(u + 4) = 0

u = 9 and u = - 4

substitute back for u

x^2 = 9

x = 3 and x = - 3

x^2 = -4 -- i am going to assume you've learned imaginary numbers; otherwise, you cannot take the square root of a negative number.

x = -2i and x = 2i