Finding the Cross Product of A and B: A Puzzling Answer?

[-EquinoX-]

Homework Statement

A = -3i + 4j and B = 2i + 3j

so I want to find AxB

Homework Equations

The Attempt at a Solution

what I got is -9k + 8k, which is -k but the answer solution says it's -17k ?

 

[G01]

You are missing a negative sign on the 8. Remember that when you take the cross product of two vectors, A and B, in the x-y plane you will get:

$$(A_xB_y-A_yB_x)\hat{k}$$

You are missing the minus sign in the above equation.

 

[G01]

EDIT: This post refers to a post deleted by the OP.The i x i and j x j terms are zero by definition. You then have:

-9(i x j)+8(j x i)

Remember that the cross product anticommutes. So if ixj=k. What does this mean for j x i?

 

[-EquinoX-]

jxi is k?