Answer:
15 m by 35 m
Step-by-step explanation:
If x represents the width of the strip lost (in meters), then the new area is ...
(20-x)(40-x) = 525
800 -60x +x^2 = 525
x^2 -60x +900 = 625 . . . . add 100 to complete the square
(x -30)^2 = 25^2
x = 30 ±25
The width must be less than 20, so the solution x=55 is extraneous. The lost width is 5 meters, so the new lot dimensions are 20-5 = 15 by 40-5 = 35.
The lot is now 15 m by 35 m.
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It is obvious that 25 is a factor of the new area, suggesting that 5 is the width of interest. "Guess and check" works well in this case.
