Question

Help please

Find the dot product, a * b.

A=6i+5j, b= -5i +4i

A.50 B. <1,9> C. -10 D. <-30,20>

I think D is right but I have doubts

Answer 1

I hope this helps you


❗i^2= -1


A=11i


B= -i


A×B= 11i×(-i)


A×B= -11.i^2


A×B=11

Answer 2

C is the answer ( i got 100%)