have 5 problems they are simplifying and write standard form #1 (5c-9)(5c+1)
(5 c - 9 ) * ( 5 c + 1 ) =
5 c * 5 c - 5 c * 9 + 1 * 5 c - 1 * 9 =
25 c ^ 2 - 45 c + 5 c - 9 =
25 c ^ 2 - 40 c - 9
5 c * 5 c - 5 c * 9 + 1 * 5 c - 1 * 9 =
25 c ^ 2 - 45 c + 5 c - 9 =
25 c ^ 2 - 40 c - 9