Derivative of y=sin(5x-4)

1. Let $u = 5 x - 4$.

2. The derivative of sine is cosine:

   $$\frac{d}{d u} \sin{\left(u \right)} = \cos{\left(u \right)}$$

3. Then, apply the chain rule. Multiply by $\frac{d}{d x} \left(5 x - 4\right)$:

   1. Differentiate $5 x - 4$ term by term:

      1. The derivative of a constant times a function is the constant times the derivative of the function.

         1. Apply the power rule: $x$ goes to $1$

         So, the result is: $5$

      2. The derivative of the constant $-4$ is zero.

      The result is: $5$

   The result of the chain rule is:

   $$5 \cos{\left(5 x - 4 \right)}$$

4. Now simplify:

   $$5 \cos{\left(5 x - 4 \right)}$$

The answer is:

$$5 \cos{\left(5 x - 4 \right)}$$