The area of a rectangular floor is described by the equation w(w-9)=252 where w is the width of the floor in meters. What is the width o the floor?

1 Answer
Tony B
Jun 3, 2016

Width (w) = 21(w)=21

Explanation:

Given:
w(w-9)=252w(w−9)=252

Multiply everything inside the brackets by ww

=>w^2-9w=252⇒w2−9w=252

Subtract 252 from both sides

w^2-9w-252=0w2−9w−252=0

Factors of 252 that have a difference of 9 are 12 and 21
We need -9 so the larger if the two is negative.

(w-21)(w+12) =w^2+12w-21w-252color(red)(" Works")(w−21)(w+12)=w2+12w−21w−252 Works

So
w-21=0" " =>" " w=+21w−21=0 ⇒ w=+21
w+12=0" "=>" "w=-12 color(red)(larr" negative value not logical")w+12=0 ⇒ w=−12← negative value not logical

Width (w) = 21(w)=21

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