gwd-6-11问一道数学题~请大家帮忙~

tanglang0921

A rectangular picture is surrounded by a boarder, as shown in the figure above.  Without the boarder the length of the picture is twice its width.  If the area of the boarder is 196 square inches, what is the length, in inches, of the picture, excluding the boarder?

A.    10
B.    15
C.    30
D.    40
E.    60

我算的过程是（2x+4）*（x+4）-（2x*x）=196

怎么算怎么是 里面的长方形长为30 因为有一个include 所以最后答案我觉得是30+4 啊  计算过程哪里错了，请大家帮帮忙

陈月

你算得是30没错，但是你再仔细看看，不是include，是excluding。意思是你只求里面的小长方形的长就ok，已经求出30，不用加四