The length of a rectangle is 4 cm more than 3 times its width. If the area of the rectangle is 15 cm^2, which equation could be used to find the width, w?
\(l=3w+4cm\)
\(15cm^2=(3w+4cm)\times w\)
\(15cm^2=3w^2+4cm\times w\)
\(3w^2+4cm\times w-15cm^2=0\) \([w = {-b + \sqrt{b^2-4ac} \over 2a}]\)
a b c
\(\large w=\frac{-4cm+\sqrt{16cm^2+180cm^2}}{6}\)
\(w=\frac{-4cm+{14cm}}{6}=\frac{10cm}{6}\)
\(\large w=1\frac{2}{3}cm\)
\(l=3w+4cm=9cm\)
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