一道GRE 求指导
问题描述：
一道GRE 求指导
A border of uniform width is placed around a rectangular photograph that measures 8 inches by 10 inches.If the area of the border is 144 square inches,what is the width of the border,in inches?
答
设 the width of the border is x inches
then （2x+10）(2x+8)-8*10=144
解出 x=3 or x=-12
这里显然 x 只能等于3