SOLUTION: Please help solve this problem: The length of a rectangle is 20 less than the width. If the area is 343, how long is the length?

Algebra ->  Rectangles -> SOLUTION: Please help solve this problem: The length of a rectangle is 20 less than the width. If the area is 343, how long is the length?      Log On


   

Question 785785: Please help solve this problem:
The length of a rectangle is 20 less than the width. If the area is 343, how long is the length?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
width =x
length = x-20
Area = L*W
x(x-20)=343
x^2-20x=343
x^2-20x-343=0
Find the roots of the equation by quadratic formula

a= 1 , b= -20 , c= -343

b^2-4ac= 400 + 1372
b^2-4ac= 1772
%09sqrt%28%091772%09%29=%0942.1%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=( 20 + 42.1 )/ 2
x1= 31.05
x2=%28-b-sqrt%28b%5E2-4ac%29%29%2F%282a%29
x2=( 20 -42.1 ) / 2
x2= -11.05
Ignore negative value
width =31.048
length = 31.048-20= 11.048

m.ananth@hotmail.ca