What is the length of the missing side of the quadrilateral shown if the perimeter is 5x^2+2x+1?

 I am thinking that the quadrilateral is not given to be a rhombus.

The perimeter is the sum of the 4 sides.

Adding 2x^2 + x -1 to 3x^2 -5x and then that sum to 4x^2 gives

9x^2 - 4x - 1 as the sum of the three given sides.

Subtract that from the given perimeter to get the missing side length.

5x^2 + 2x + 1 - (9x^2 -4x -1) =

-4x^2 + 6x + 2

step-by-step explanation:

here's what happens:

1) the graph of f   = x^2 is shifted 2 units to the right.

2) the resulting graph is reflected in the x-axis, so that the parabola now opens down.

3) this final result is transformed up by 5 units.