Which of the following functions describes the sequence 1, 3, 7, 15, 31, 63, 127, … ?

A. f(1) = 1,f(n) = f(n − 1) + n for n > 1.
B. f(1) = 1,f(n) = 2n + 1 for n > 1.
C. f(1) = 1,f(n) = f(n − 1) + 2(n − 1) for n > 1.
D. f(1) = 1,f(n) = 2f(n − 1) + 1 for n > 1.

What is 1/3x5 on anuber line what does it look like on a number line

Aquadrilateral has exactly one pair of parallel sides. which name best describes the figure?

Look at the figure below: triangle abc is a right triangle with angle abc equal to 90 degrees. the length of ac is 5 units and the length of ab is 4 units. d is a point above c. triangle adc is a right triangle with angle dac equal to 90 degrees and dc parallel to ab. what is the length, in units, of segment cd?