Question

The width of a rectangle is the length minus 4 units. The area of the rectangle is 21 units. What is the width, in units, of the rectangle?​

Answer 1

Answer:

Step-by-step explanation:

$W=L-4\\ \\ L=W+4\\ \\ A=LW\\ \\ A=(W+4)W\\ \\ A=W^2+4W\\ \\ A=21\\ \\ W^2+4W=21\\ \\ W^2+4W-21=0\\ \\ (W+7)(W-3)=0\\ \\ W>0\\ \\ W=3u$