Factor the following equation completely: x^4+8x^2-9

Answer 1

Hi Owen...if you look at the problem, you need x^4, which is x^2 times x^2

(x^2 )(x^2 )

Then think what can you multiply to get 9? 3x3 and 9x1...3+3 or 3-3 will not give you 8 when you use FOIL, BUT 9-1 does = 8....and you need - 9 and + 8 for the original equation, which means the 9 must be positive and the 1 negative to result in positive 8