Write a recursive and explicit formula for the following sequence: 21, 24, 27, ...

Write each expression in exponential form and find its value. 3 x 3 x 3

How many $20 bills do you need to have to make $280

36x2 + 49y2 = 1,764 the foci are located at: (-√13, 0) and (√13,0) (0, -√13) and (0,√13) (-1, 0) and (1, 0)edit: the answer is (- the square root of 13, 0) and (the square root of 13, 0)