If x^2=-1, What is the value of x?

If x is 6, then 7x= a. 13 b. 42 c. 42x d. 76

You deposit $5000 each year into an account earning 3% interest compounded annually. how much will you have in the account in 30 years?

What effect would doubling all the dimensions of a triangular pyramid have on the volume of the pyramid? explain your reasoning.