Precalculus Examples

$\cos^{4} (x) - \sin^{4} (x) = \cos (2 x)$

Step 1

Subtract $\cos (2 x)$ from both sides of the equation.

$\cos^{4} (x) - \sin^{4} (x) - \cos (2 x) = 0$

Step 2

Graph each side of the equation. The solution is the x-value of the point of intersection.

$x \approx 0, - 0.1, 0.1, \frac{1}{5}, - 0.3, 0.3, - \frac{2}{5}$

Step 3