# math

posted by Jane

A parallelogram has an area of 8x^2 - 2x -45. The height of the parallelogram is 4x + 9. I know the formula for a parallelogram is A=bh. Please work and explain how I get the length of the base of the parallelogram. Thanks

1. Steve

since a = bh and they give you a polynomial for a and h, you have to expect that b = a/h and (4x+9) divides (8x^2 - 2x -45)

In fact, 8x^2 - 2x -45 = (4x+9)(2x-5)

so, b = 2x-5

If they had given you numbers, you'd have had no trouble doing the division. Don't be confused by their efforts to cloak the underlying simplicity of the question.

2. Wayne

Factor(unfoil) the area to get:
(2x-5)* (4x+9). When you divide that by the height, the result is the length of the base: (2x-5)
Not sure if you're solving for x, but I don't think that there's enough information. Let me know if this helps you!

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