Question

i need my answers checked

Answer 1

@Zarkon

Answer 2

why you think it true ?

@ThisGirlPretty

Answer 3

well for a simple reason, the matrices are reversed

Answer 4

yes so and the diagramm ?

Answer 5

than you check the diagramm there is that for x= 2 => y = 8 and the reflection diagramm how is it ?

Answer 6

for y= 2 you see the x = 8

right ?

Answer 7

yeah

Answer 8

so from this result that your answer is correct

Answer 9

@ThisGirlPretty

Answer 10

@Vocaloid

Answer 11

good

Answer 12

@Mercury

Answer 13

hm not quite

the given matrix
[1 0
0 -1]

reflects across the x-axis

what image is this?

Answer 14

uh...i dont really know how to read matricies that well..., care to give me a little refresher?

Answer 15

notice how the matrix on the left is

\[\left[\begin{matrix}1 & 0 \\ 0 & -1\end{matrix}\right]\]

this indicates a reflection across the x-axis

from geometry, this is what a reflection across the x-axis looks like:

Answer 16

notice how the x-axis is acting as the mirror between the two images

apply this logic to your problem to see what the correct choice is.

Answer 17

so the first one?

Answer 18

good

Answer 19

good

Answer 20

good

Answer 21

hm. technically none of these are correct because of the order of the matrix multiplication

however, since the first two coordinates are positive, that means the first two coordinates should be negative in the reflection

therefore C is the only option that could potentially be viable

bad question :S

Answer 22

you just need to put the coordinates of X into a 2x3 matrix
start by putting the coordinates of X into the first column

the coordinates of X are (0,-5)

so the first column of the matrix is

0
-5

then keep going across with points Y and Z

Answer 23

oh wait I didn't see you already picked one of the choices whoops

the second one is correct

Answer 24

just have to know this one, it's ~center~

Answer 25

remember, for matrices the inner dimensions have to match

you have a 1 x 4 multiplied by a 3 x 1 matrix

so 4 and 3 (the inner dimensions) are not equal, this matrix product is undefined

Answer 26

not quite

it's only rotating the shape 30 degrees counterclockwise (to the left)

so see which image takes the triangle and rotates it 30 degrees CC without reflecting it

Answer 27

the last one?

Answer 28

the tip of the image should be moving left according to this diagram

Answer 29

ah, the first one

Answer 30

good

Answer 31

good

Answer 32

hm not quite

start by listing out the dimensions of each matrix, ex:

A * B multiplied by C * D

then the outer dimensions (in this case, A and D) determine the product dimensions

Answer 33

3x2?

Answer 34

remember dimensions are written as:

number of rows * number of columns

Answer 35

for the first matrix how many rows and columns are there?

Answer 36

2 and 3

Answer 37

good so the dimensions of matrix 1 are 2*3

repeat this process w/ the second matrix

Answer 38

3 and 2

Answer 39

good so you have

2*3 by 3*2

so if you look on the outer dimensions you have 2*2 = your sol'n

Answer 40

hm not quite

to multiply matrices consider the first row of the first matrix, and the first column of the second matrix:

Answer 41

multiplying the blue gives us

(0)(-1) = 0

multiplying the green gives us

(-1)(2) = -2

adding these together gives us -2 as the first entry in the product

Answer 42

hm. technically none of the answer choices are actually the correct product

what happens if you pick the blank option?

Answer 43

alright

can you try repeating this multiplication process with the first row of the first matrix and the second column of the second matrix? the result will let you distinguish what the correct sol'n is

Answer 44

it was the blank one wasnt it?

Answer 45

right

Answer 46

remember that the distributive property is A(B+C) = A*B + A*C

what's it called when you can switch the order of multiplication and still get the same product?

Answer 47

commuinative

Answer 48

good so commutative = your sol'n

Answer 49

if i remember, this one is the same, right? 2x2?

Answer 50

good

Answer 51

hm, not quite, remember what we did before

first take the first row of the first matrix & the first column of the second matrix

Answer 52

then multiply the first terms together

then multiply the second terms together

Answer 53

giving us

(-2)(2) = -4
and
(3)(1) = 3

adding these together gives us -1 as the first term not -7

Answer 54

repeat this procedure for the

first row of the first matrix
and
second column of the second matrix

Answer 55

basically you want to follow this pattern

Answer 56

gonna be eating dinner soon, let me know when you've attempted a solution

Answer 57

i've tried it and got the third one

Answer 58

@Mercury that it?

Answer 59

hm not quite

let's redo the last set of multiplication, second row of the first matrix & the second column of the second matrix

Answer 60

we have 3(0) + (-4)(-3) which is 12 not -12

therefore it's the last choice