4. If the pattern below continues, what number likely comes next? 9, 12, 15, 18, 21, ?

Find the midpoint m of z1=(8+5i) and z2=(12+3i)

Which of the following would be a good name for the function that takes the weight of a box and returns the energy needed to lift it?

If the ratio of sum of the first m and n terms of an ap is m2 : n2 , show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1).