What is d/dx [e^(8x) cos(4x)]?

C. e^(8x)(8cos(4x)-4sin(4x))

Step 1: apply the product rule. Step 2: derivative of e^(8x) is 8e^(8x) and derivative of cos(4x) is -4sin(4x), so answer is e^(8x)(8cos(4x)-4sin(4x)). Step 3: tip: in products, differentiate both factors.

Step 1: product rule लगाइए। Step 2: derivative e^(8x) का 8e^(8x) और cos(4x) का -4sin(4x) है, इसलिए answer e^(8x)(8cos(4x)-4sin(4x))। Step 3: tip: product में दोनों parts को differentiate करें।