Find the intervals for which `f(x)=x^4-2x^2` increasing or decreasing.

Explanation

To determine the intervals where the function \( f(x) = x^4 - 2x^2 \) is increasing or decreasing, we will follow these steps:

### Step 1: Find the derivative of the function
To analyze the increasing and decreasing behavior of the function, we first need to find its derivative.

\[ f'(x) = \frac{d}{dx}(x^4 - 2x^2) \]
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