x*Y=4X+5Y,那么3*4=( )A.21 B.32 C.16

问题描述:

x*Y=4X+5Y,那么3*4=( )
A.21 B.32 C.16

B将3代入X,4代入Y即4x3+4x5得32

3*4=4X3+5X4=32

3*4=4×3+5×4=32
选B