Question

Solve the matrix equatin for x and y. ill attach the file. its number 12 on pg 42

Answer 1

are you doing question 12 on page 42?

Answer 2

Yes

Answer 3

the 3 out front of the first matrix means multiply every number inside the matrix by 3
can you do that?

Answer 4

you get 6 new numbers

now subtract the 2nd matrix. that means top left of the 1st matrix (after being multiplied by 3) minus the top left number in the 2nd matrix:
if you did it right you would see
3*3-2 =9-2 =7
notice that this matches the top left number in the answer matrix.

Answer 5

you need algebra to do the top right numbers.
what do you have so far?

Answer 6

so far i sfter multiplying the first matrix by 3 i got :
9 -2x+3] [2 -2x] 7 8
6 12 ] -[0 5 ]= 6 7
-y+3 6 ] [-2y -2] 0 8

Answer 7

ok, you can multiply 2 numbers but you are adding for the variables
If you had 2 x's and you tripled the number of x's (multiplied by 3) how many x's do you have?

Answer 8

If it helps, think of x as something real like a cow, you have 2 cows, multiply by 3, how many cows?
(for -2x, it does not quite make sense, but you get 3* -2x)

Answer 9

hmm no it doesn't. Is there another way to solve it because in this math book other similar problems are done like this.

Answer 10

this is an important idea (multiplying 3* -2x) so it's worth getting it.
to get the idea, let's think of it like this
3* -2x means the same thing as 3 * 4 (for example) : 4+4+4
but instead of 4 we have -2x: -2x + -2x + -2x

can you get the answer?

Answer 11

-6x?

Answer 12

ok so hows would this be used in this

Answer 13

maybe we should do an easier problem first 3* 1x: 1x+1x+1x or simple x+x+x= 3x
or
3*2x= 2x+2x+2x (you have 2 x's add 2 more x's you get 4x's. add 2 more x's to get 6x)

-6x is correct.
(fixed typo)

Answer 14

now fix where you multiplied 3* -y

Answer 15

so then it would be -9y?

Answer 16

3* -y is not -9y ( 3* -3y is -9y)

here is another way to think of it: -y is short hand for -1*y
so 3*-y is the same thing as 3*-1*y
if you simplify, what do you get?

Answer 17

you multiply the numbers, but leave the y alone.

Answer 18

oh yea srry i still had the other way written in my paper i confused me sorry so it would -3y?

Answer 19

yes -3y

now look at the top right "number" in the first matrix. it is
-6x
now subtract (because we are subtracting the 2nd matrix)
the top right number of the 2nd matrix
this equals the top right number of the last matrix.
can you write down the equation?

Answer 20

ok so now i subtract the elements in the 1st matrix by the elements in the 2nd matrix? ifd so, i got:
7 -4x] 7 8
6 -1 ] = 6 7
-y 8 ] 0 8

Answer 21

notice that all the pure number elements match. example, the top left 7 = top left 7 of the other matrix. (although I would check the middle row, right number, because -1 does not equal 7, you goofed there)

I think it should have been 12-5=7 (not sure how you got -1)

Answer 22

now let's concentrate on the top right
-4x = 8

can you solve this?
I would divide both sides by -4

Answer 23

ok i got x= -2 and y =0

Answer 24

yes

Answer 25

oh and i see why i got - 1 one the second right number, its because i forgot to multiply 4 by 3 and after i did i got 12 then subtracted by 5 and now i have the corresponding element

Answer 26

btw, notice that you only had to concentrate on the top left entries to find x, and ignore the rest of the matrix. so if I were doing this problem I would have said:

3* -2x - (-2x)= 8
and then solved for x.

Answer 27

*top right

Answer 28

oh ok so you would just do the whole solving .

Answer 29

I would just look at the entry with the x in it (top right), and looked at only that entry in the other matrices. (because the question asked only for x and y, not all the numbers)

Answer 30

oh ok so could you give me another similar example so that i can try and see if i now understand it?

Answer 31

try question 11, just before Q12

Answer 32

ok let me see what i get then.

Answer 33

ok i got x=-3 y=1

Answer 34

yes
2 * 2x = -12
4x= -12
x= -12/4 = -3

and
2*3 = 6y
6=6y or 6y=6
y= 6/6=1

and the bottom right does not give us an answer for y
2* -3y= -6y
-6y= -6y
or y=y
or 1=1
true, but not helpful for finding what y is.

Answer 35

You seem to be learning this, but you might need practice on the rules of algebra.
just post questions to the site and people will help you if you are stuck.

Answer 36

ok do you still have time to help me on 14?

Answer 37

ok

Answer 38

ok so on 14 would the equation be the 1st matrix subtracted by the 2nd matrix =12?

Answer 39

the hardest part is figuring out what they want done.

they give costs for a full year. this year and next year.
if we subtract next year's numbers minus this year's numbers we get the amount the price went up. I would do that first.

that will be how much the price went up for the year. If we pay every month, divide by 12 to get how much it goes up per month

Answer 40

oh ok yea thats more common sense, so let me try that and see what i get.

Answer 41

ok so i got :
54.8 108.6
5.5 16
-10.6 -25.5

Answer 42

Is that the yearly difference? And where are the pennies (2 numbers to the right of the decimal point)

Answer 43

subtract the 2 numbers, divide by 12, then round

Answer 44

yes i subtracted next year's matrix by this year's matrix and ok so use all those those numbers that i showed you and divide them all by 12 right?

Answer 45

yes, but you have 54.8 for the top left number. I think it should be
780.36-725.52= 54.84

Answer 46

oh ok im doing this by calculator so i think its rounding by itself to the tenth's place do you know how take that off my TI-30XIIS texas calculator?

Answer 47

maybe press 2nd (top left) then sci/eng then flo ? not sure.

Answer 48

oh i got it now i pressed the fixed button and place it to have 3 decimals places

Answer 49

let me correct all of them and tell you what i got.

Answer 50

ok i got:
4.57 9.05
0.46 1.36
-0.88 -2.12

Answer 51

ok except for 1.36

Answer 52

oh right it's 1.34

Answer 53

yes.

Answer 54

ok so that matrix is the solution for the problem right

Answer 55

yes

Answer 56

Alrigthy ,well THANK YOU VERY MUCH! Really appreciate your time in helping me :)

Answer 57

yw

Answer 58

I just learned this today and it advanced math 3 yet im taking math 2 so yea

Answer 59

* i have

Answer 60

i mean i have math 2 but were starting math 3