If y = 5cos2x, what is the amplitude?

Quadrilateral efgh was dilated with the origin as the center of dilation to create quadrilateral e'f'g'h'. the quadrilateral was dilated using a scale factor of 2.5. the lengths of the sides of quadrilateral efgh are given. what is the length of side f'g'?

Did i do these question right? if not explain why it’s wrong?

What is the solution to this system of linear equations? x + y = 4 x - y = 6 (4,6) (6,4) (5, -1) (-1,5)