The expression (cos(x3)) represents the cosine of the cube of (x). This is a trigonometric function, and without specific values for (x), it cannot be simplified further into a single numerical value. The function (cos(x3)) will vary depending on the value of (x).
If you are looking for the derivative of (cos(x3)) with respect to (x), it can be found using the chain rule. The derivative is:
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