a=(1,-2)b=(3,2)c=(3,2)∴a+2b=(1,-2)+2(3,2) =(1,-2)+(6,4) =(7,2)∴(a+2b)*c=(7,2)*(3,2) =21+4=25
你这应该是向量的运算吧!向量a+2b=(1,-2)+ 2(3,2)=(7,2)(a+2b)*c=21+4=25
so easy!(1+6)*3=21(-2+4)*2=421+4=25