How to find the measurement of a parallelogram

What number should be added to the expression x^2+3x+ in order to create a perfect square trinomial? 3/2 3 9/4 9

The diagonals of a quadrilaretral intersect at (-1,4). one of the sides of the quadrilateral is bounded by (2,7) and (-3,5) determine the coordinates of the other side in order for the quadrilaretral to be a square.

Astore has apples on sale for three dollars or 2 pounds how many pounds of apples can you buy for nine dollars if an apple is approximately 5 ounces how many apples can you buy for nine dollars