SOLUTION: area of big rectangular room is 300m^2 .if the length were decreased by 5 m and the breadth increased by 5m ; area would be unaltered. find the length of room

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Question 938645: area of big rectangular room is 300m^2 .if the length were decreased by 5 m and the breadth increased by 5m ; area would be unaltered. find the length of room

Answer by lwsshak3(11628) About Me  (Show Source):
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area of big rectangular room is 300m^2 .if the length were decreased by 5 m and the breadth increased by 5m ; area would be unaltered. find the length of room
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let x=length of room
let y=breadth of room
area=length*breadth=x*y=300
y=300/x
altered length and breadth:
x-5=length
y+5=breadth
area=(x-5)(y+5)=300
%28x-5%29%28300%2Fx%2B5%29=300
%28x-5%29%28%28300%2B5x%29%2Fx%29=300
%28x-5%29%28300%2B5x%29=300x
300x-1500+5x^2-25x=300x
5x^2-25x-1500=0
x^2-5x-300=0
(x+15)(x-20)=0
x=20
length of room=20m