VCAA 2010 Exam 1 Help

[Duckdodgers]

Hey, I've done good for the majority of this one, except for Module 6 (Matrices) Question 3.
Could anyone take me through the steps on how they got this? My book is useless on finding out how.

[Natters]

ice cream =x
soft drink = y    costs that is

one IC+3 SD=x+3y=9 dowwa
2x+5y=16 dowwa

thus umm idk how to type matrices, ill just do it how i put them on my calc; [ [ 1,2] [3,4] ] is |1  2|
[ [1,3]  [2,5] ] *  [

• [y] ] =  [[9] [16]]                                                                                    |3 4 |

so [

• [y] ] is [ [9] [ 16] ] * [ [1,3] [2,5] ]to the power of negative one

so you just gotta find the determinant and that shiz of that matrix, and ur done

[Keo]

let x=ice cream and y= soft drinks
catherines shop = $9 for 1 ice cream and 3 soft drinks
therefore this gives
 x+3y=9
and we know the total cost of ice creams of a different sum
which in turn gives the equation
2x+5y=16

we turn this into matrix form making it (imagine that brackets are together)
|1   3| |x|  = [9]
|2    5| |y|  = [16]

to find what the matrix x y equals to
we find the inverse of
|1   3| ^ -1
|2    5|

which equals
|-5  3|
|2  -1|

we times this now by
|9
|16
 therefore to find x and y
we do this

|-5  3|  * |9
|2  -1|     |16
 therefore E is your answer

[Natters]

mine is so much shitter than yours
lmfao

[Duckdodgers]

Ohhhhh, wow that's simple. Thanks guys, I just didn't get what answer they were looking for, cheers =).

[Keo]

mine is so much shitter than yours
lmfao

still good! i understand it

[RobDog]

Nvm