NEED HELP ASAP WILL MARK BRAINLIEST

Describe how to determine the average rate of change between x = 1 and x = 3 for the function f(x) = 3x^3 + 1. Include the average rate of change in your answer.

The function a represents the cost of manufacturing product a, in hundreds of dollars, and the function b represents the cost of manufacturing product b, in hundreds of dollars. a(t) = 5t + 2 b(t) = 7t - 2t +4 find the expression that describes the total cost of manufacturing both products, a(t) + b(t). a. 7t^2 - 7t + 2 b. 7t^2 + 3 +6 c. 7t^2 + 7t - 6 d. 7t^2 - 3t + 6

Will mark brainliest! ( explain the answer too, it can be one sentence)

The formula to determine energy is e=1/2mv2? what is the formula solved for v?