Question

Given that; a=(2,-3), b=(3,4), c=(-1,5), find the number.
(a-b)*(b+c)

Answer 1

just so you know this section is with the dot product.

Answer 2

\[a - b = <2,3> - <3,4> = <2-3, 3-4> = <-1,-1>\]
\[b + c = <3,4> + <-1,5> = <3-1, 4+5> = <2,9>\]
\[(a-b)\cdot(b+c) = <-1,-1>\cdot<2,9>\]

Answer 3

\[=-1\cdot 2 + -1\cdot 9 = -2 -9 = -11\]

Answer 4

(-1,-7)*(2,9)
=>-65 is the answer.

Answer 5

polpak u missed in the first step i guess...

Answer 6

Oh, woops.. I missed the -3.

Answer 7

In any case the process is the same.

Answer 8

I have 3 instead of -3.

Answer 9

Thanks you guys!!