# Homework Help: Find all roots of a function

1. Mar 13, 2010

### Dustinsfl

x^4 + 7x^2 + 6 =0

I know the answers are imaginary but I don't remember how to solve this equation.

2. Mar 13, 2010

### boboYO

Let t=x^2 and solve for t. Then once you have t, you can easily find x.

3. Mar 13, 2010

### Dustinsfl

If I do that and solve for t, I obtain two real solutions when all 4 all imaginary.

4. Mar 13, 2010

### boboYO

using quadratic formula:

$$x^2=\frac{-7\pm \sqrt{49-24}}{2}$$
$$x^2=\{-6,-1\}$$

both values of x^2 for negative, so all 4 values of x are imaginary. Check your working?

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