Question

Find real or imaginary solutions of the equation by factoring x^4-10x^2-9=0 Find real or imaginary solutions of the equation by factoring x^4-10x^2-9=0 @Mathematics

Answer 1

Let x^2 be y
x^4 =y^2
replacing them in equation we get
y^2-10y-9=0

Answer 2

bleep, are you sure this is a -9?

Answer 3

i almost did the same thing, sumanthy!!!

Answer 4

Yes , I just deleted the post as I checked it -9 :) Thanks Mandolino

Answer 5

bleep are you checking?

Answer 6

my fail positive 9

Answer 7

\[x^4-10x^2-9=0\]factor as a trinomial: either use the substitution that sumanthy suggested or just write x^2 where you would usually write x\[(x^2-9)(x^2-1)=0\]factor each binomial as a difference of two squares\[(x-3)(x+3)(x-1)(x+1)=0\]set each factor equal to zero to solve\[x-3=0 \cup x+3=0 \cup x-1=0 \cup x+1=0\]solution set is\[\left\{ -3,-1,1,3 \right\}\]

Answer 8

When you have trinomial where the ratio of the exponents is 4:2 (as we have here) or 2:1, then you can use quadratic equation methods. So I just looked for factors of +9 that sum to -10; those are -9 and -1; this is FOIL in reverse

Answer 9

good?

Answer 10

yeah i get it now thanks. we'll see if i understand the harder ones but i understand the basics

Answer 11

cool! :})