If y = 3x^4 -2x^3-7x+5, find dy/dx.

Create a real-life situation and create a system and show how it might be modeled algebraically with a system of equations (or inequalities) show all work include a few sentences explaining the situation, your variables of choice and what each represents, and how you would set it up and solve it algebraically. !

Prove that the value of the expression 7^8–7^7+7^6 is divisible by 43.

Answer asap! urgent! will give brainliest!