SOLUTION: I would appreciate any help walking me through this homework question that I have. Find all real zeros of the functions listed below. * f(x)=-7x^4+343x^2 * f(x)=x^4-16x^2+15

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: I would appreciate any help walking me through this homework question that I have. Find all real zeros of the functions listed below. * f(x)=-7x^4+343x^2 * f(x)=x^4-16x^2+15      Log On


   

Question 87620: I would appreciate any help walking me through this homework question that I have.
Find all real zeros of the functions listed below.
* f(x)=-7x^4+343x^2
* f(x)=x^4-16x^2+15
Answer by longjonsilver(2297) About Me  (Show Source):
You can put this solution on YOUR website!
1. +f%28x%29=-7x%5E4%2B343x%5E2+
+f%28x%29=-7x%5E2%28x%5E2-49%29+
+f%28x%29=-7x%5E2%28x%2B7%29%28x-7%29+

2. think of +x%5E4-16x%5E2%2B15+ as +y%5E2-16y%2B15+ where y=x%5E2. You can factorise this quadratic in y by looking and then re-write y as x^2 for each solution and find out what x is for each.

cheers
Jon