2x+3y=2007 2(3x-2y)-(x-y)+(-x+9y)等于多少
问题描述：
2x+3y=2007 2(3x-2y)-(x-y)+(-x+9y)等于多少
答
(1)2007的2次方减2006乘2008的值 =2007^2-(2007-1)(2007+1) =2007^2-(2007^2-1) =2007^2-2007^2+1 =1 (2)5a的2次方b乘(-34ac) =5*(-34)a^2b*ac =-170a^2b^2c (3)a^m=2a^n=3 a^n=3/2 a^(2n+m) =(a^n)^2*a^m =(3/2)^2*...