SOLUTION: area of a rectangle= 220 square feet. find the dimensions of the figure x-9 is the width and the length is x.

Question 178628: area of a rectangle= 220 square feet. find the dimensions of the figure
x-9 is the width and the length is x.
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!

Area formula:

. Since

, and A is given as 220, just substitute.

.

Distribute and add -220 to both sides:

.

Since

and

, this quadratic factors.

The quadratic, of course, has two roots. One of these roots will be negative which is an absurd result when calculating the length of something. This is an extraneous root introduced when the variable was squared in the process of solving the problem -- exclude it. The positive root is the correct value for the length of the rectangle, and the width can be calculated directly from that value.

You should be able to handle it from here.

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