I have three more questions I do not understand.

1. Two points (-1,1) and (3,-2) are graphed on a coordinate plane.
What is the shortest distance between the points?
A. 3
B. 4
C. 5
D. 7
I have no idea how to do this.

2. Which expression represents the nth term in the sequence 1, 3, 5, 7, 9, n...?
A. n-2
B. 2n(squared, exponent 2)-1
C. 2n-1
D. 2(exponent n)-1
I know that n is 11, but I don't get the expressions in the answers.

3. Which statement is correct?
A. All intergers are rational numbers.
B. All irrational numbers are whole numbers.
C. A real number must be a rational number.
D. A repeating decimal is an irrational number
I think it's either A or C.