Please help! Nearly done with the assignment!

How many different ways can you make change for $.50 using only nickels,dimes, and quarters?

Proceed as in example 3 in section 6.1 to rewrite the given expression using a single power series whose general term involves xk. ∞ n(n − 1)cnxn − 2 n = 2 − 4 ∞ ncnxn n = 1 + ∞ cnxn n = 0

Find dy/dx using implicit differentiation ln(20+e^xy)=y