Why is 6 over 8 greater than 5 over 8 but less than 7 over 8

Find the average rate of change for f(x) = x2 − 3x − 10 from x = −5 to x = 10.

Which of the following of the following sets of side lengths could not form a triangle?

How do i start to solve? would appreciate a walk-thru! a bird sitting 16ft above the ground in an apple tree dislodges an apple. after how many seconds does the apple land on the ground? (assuming that no branches will interfere with it's fall)