PLEASE HELP AS FAST AS POSSIBLE PLEASE!! Prove: if the diagonals of a quadrilateral bisect each other, then the quadrilateral is a parallelogram.

ABCD is a parallelogram

Which expression is equivalent to the expression shown?

Luke started a weight-loss program. the first week, he lost x pounds. the second week, he lost pounds less than times the pounds he lost the first week. the third week, he lost 1 pound more than of the pounds he lost the first week. liam started a weight-loss program when luke did. the first week, he lost 1 pound less than times the pounds luke lost the first week. the second week, he lost 4 pounds less than times the pounds luke lost the first week. the third week, he lost pound more than times the pounds luke lost the first week.

In which direction does the left side of the graph of this function point? a(x) = 3x - x2 + 4x - 2