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?

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Answer 1 · 2016-06-03T18:34:09

Width #(w) = 21#

Given:
#w(w-9)=252#

Multiply everything inside the brackets by #w#

#=>w^2-9w=252#

Subtract 252 from both sides

#w^2-9w-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")#

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

Width #(w) = 21#