Question

Please help

What is the solution of matrix equation
[2 5] [3]
[1 3] x= [-1]

Answer 1

does that x have brackets around it?

Answer 2

No it doesnt

Answer 3

ok... hmm. That should be a matrix with two rows and one column there. So I would set it up like\[x=\left[\begin{matrix}x_1 \\ x_2 \end{matrix}\right]\] and then solve just like the other one we did. You're answer will be a matrix with 2 rows and one column

Answer 4

alright and I got [14]
[ -5]

Answer 5

Great job!

Answer 6

I was wondering if thats correct

Answer 7

it absolutely is!

Answer 8

Thank you

Answer 9

@caseyrt can you help me with this question ?

Which matrix equation has the solution X = [3]
[-5]

Answer 10

sure, are there some answer options?

Answer 11

A.[9 5] [2]
[7 -4] x =[1]

B. [-9 5] [2]
[7 4] x =[1]

C.[9 5] [2]
[7 4] x =[1]

D. [9 5] [2]
[-7 4] x =[1]

Answer 12

ok so we just need to put the little matrix they give us in the place of x in each place and see which one comes out being true! ...

Answer 13

so for the first one, 9*3-5*5=2

Answer 14

so the top is correct

Answer 15

but the bottom is 7*3+4*5=41 which is obviously not 1 like it says it should be, so A isn't it

Answer 16

but the top part of A was right, so the answer will have its top part the same as A's, which means the answer isn't B, either. Of the two that are left, can you find out which one has the correct bottom row?

Answer 17

it would be .d

Answer 18

d would give us -7*3-4*5... which I think is not 1... do you see why that is?

Answer 19

Yes because that equals -41

Answer 20

yah I guess I meant to ask do you see why I set up the numbers the way I did?

Answer 21

because that's really the only hard thing about these problems... but it can be pretty tough!

Answer 22

Alright so the answer would be C. then

Answer 23

right.

Answer 24

Thanks