Question

设a=(1,-2),b=(3,2),c=(3,2),则（a+2b)*c等于?

Answer 1

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