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Find a ⋅ b. a = 7i - 4j, b = 4i + 3j (5 points)

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1 vote
See the attachment below.
Hope this helps.
Find a ⋅ b. a = 7i - 4j, b = 4i + 3j (5 points)-example-1
User Alan Mroczek
by
7.5k points
4 votes
Hello there!

We must set up this equation to find a * b.

We know:

a = 7i - 4j

b = 4i + 3j

(7i - 4j)(4i + 3j)

Let's use FOIL

First

Outside

Inside

Last


First: 7i * 4i

Outside: 7i * 3j

Inside: -4j * 4i

Last: -4j * 3j


7i * 4i = 28i^2

7i * 3j = 21ij

-4j * 4i = -16ij

-4j * 3j = -12j^2


28i^2 + 21ij - 16ij - 12j^2

Now we must simplify

21ij - 16ij =5ij

28i^2 - 12j^2 + 5ij

Your answer is 28i^2 - 12j^2 + 5ij

I hope my answer helped you!

~ Fire


User MoRe
by
8.3k points

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