Which of these expressions is equivalent to – 4(5 – 2x)?

Which interval for the graphed function contains the local maximum? [–3, –2] [–2, 0] [0, 2] [2, 4]

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).

How do i simply this expression (quadratic formula basis) on a ti-84 or normal calculator?