对于有理数a,b,定义a⊙b=3a+2b,则【(x+y)⊙(x-y)】⊙3x,化简后得( ) 0对于有理数a,b,定义a⊙b=3a_数学解答

对于有理数a,b,定义a⊙b=3a+2b,则【(x+y)⊙(x-y)】⊙3x,化简后得( ) 0
对于有理数a,b,定义a⊙b=3a+2b,则【(x+y)⊙(x-y)】⊙3x,化简后得( ) 0 5x 21x+3y 9x+6y

人气：349 ℃　时间：2019-10-11 17:41:25

解答

a*b=3a+2b
(x+y)*(x-y)=3(x+y)+2(x-y)=3x+3y+2x-2y=5x+y
(x+y)*(x-y)*3x=(5x+y)*3x
=3(5x+y)+6x
=15x+3y+6x
=21x+3y
答案：C.21X+3y