Answer:
- 525 = (w+4)(w)
- 21 ft by 25 ft
Step-by-step explanation:
Let w represent the width of the floor. Then the length of the floor is (w+4) and its area is ...
A = LW
525 = (w+4)(w)
w^2 +4w -525 = 0
(w -21)(w +25) = 0 . . . . factor the above
Solutions are ...
w = 21, w = -25
We are interested in the positive solution: w = 21.
The floor is 21 feet wide and 25 feet long.
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<em>Alternate solution</em>
Sometimes, when the factors aren't obvious, it works well to write an equation for the average of the dimensions. Here, we can represent that with x, and use (x-2) for the width, and (x+2) for the length. Then we have ...
525 = (x-2)(x+2) = x^2 -4
529 = x^2
√529 = 23 = x
Then w=23 -2 = 21, and the length is w+4 = 25.
Lines are in the form y=mx+b, where m is the slope and b is the y-intercept. This line is thus y=9/4x-14, so C is correct. Multiplying by four, we get 4y=9x-56. Adding 56 and subtracting 4y, we see that 9x-4y=56, and multiplying by -1, we get 4y-9x=-56, so A is also correct. At this point, it is clear that B and D are incorrect, so A and C only are correct.
