Need help with getting the answer

Which expression is equivalent to 16 in exponential form? a) 4 × 4 b) 8 × 2 c) 23 d) 24

Which expression and diagram represent “renee biked four times as far this month as last month”?

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)