The power rule is quite difficult to learn and comprehend at first, however, it gets easier as time goes on!

These answers are:

1. 4x

2. 15x^4+24x^3+3

3. 16x^7+15x^4

The power rule states: b^a derivative is ab^a-1 .. Basically subtract 1 from the exponent and multiply the base b by a.

Any other questions feel free to ask.