SOLUTION: question-A piece of cloth costs Rs.35.If the length of the piece would have been 4 mtr longer and each metre costs Rs.1 less,the cost would have remained unchanged.How long is the

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Question 560531: question-A piece of cloth costs Rs.35.If the length of the piece would have been 4 mtr longer and each metre costs Rs.1 less,the cost would have remained unchanged.How long is the piece?

Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
let the length of piece of cloth be x
let the rate per metre be y
xy =35
x=35/y
4 mtr longer
and Re 1 less
(x+4)(y-1)=35
both are equal to 35
equate the two
(x+4)(y-1)=xy
xy-x+4y-4 =xy
xy cancels off
-x+4y = 4
substitute x in the equation
-35/y +4y = 4
multiply equation by y
-35y/y + 4y*y= 4y
-35+4y^2=4y
4y^2-4y-35=0
Find the roots of the equation by quadratic formula

a= 4 , b= -4 , c= -35

b^2-4ac= 16 + 560
b^2-4ac= 576
%09sqrt%28%09576%09%29=%0924%09
x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=( 4 + 24 )/ 8
x1= 3.5
x2=( 4 -24 ) / 8
x2= -2.5
Ignore negative value
Rate per metre = Rs. 3.50
Price of cloth is Rs.35
35/3.5 = 10 metres
Length of cloth = 10 metres
m.ananth@hotmail.ca