第一道：if the length of one of the legs of a right triangle is decreased by 10%,and the length of the other leg is increase by 20%,then what is the approximate percent change in the area of the triangle?第二道：if m is a positive integer,and if 3+16/m is an interger less than 19,which of the following must be true of A:m=19,B:m is even,C:m=16,D:m is a prime number E:m is a multiple of four 感激不尽!
问题描述：
第一道：if the length of one of the legs of a right triangle is decreased by 10%,and the length of the other leg is increase by 20%,then what is the approximate percent change in the area of the triangle?第二道：if m is a positive integer,and if 3+16/m is an interger less than 19,which of the following must be true of A:m=19,B:m is even,C:m=16,D:m is a prime number E:m is a multiple of four 感激不尽!
答
楼上两个.额.所以楼主看过来吧~!
1.一个边a减少10%一个b少20%.设a长10 cm b长20cm,面积100,减少后a 9 b16,面积72,减少28% （遇到这种题假设就行了）
2.一个正数经过那个式子后既是整数又比九小.那么16/m+3