The width of a rectangle is 3 inches less than its length. The area of the rectangle is 340 square inches. What are the length and width of the rectangle?
If the width is w and the length is l, then l-3=w. In addition, l*w=340. Substituting l-3 for w, we get l*(l-3)=340 and l^2-3l=340, then l^2-3l-340=0. Using the quadratic formula, we get l= (3+-sqrt(9+1360))/2=(3+-37)/2 = 20, -17. Since -17 can't be the length, the length is 20. In addition, since l-3=w, w=17