SOLUTION: okay, i'm not very good at matrices... [4 2]____[-6 0] [5 1]*A= [-15 3] (find matrix A) please help i'll be very grateful!! ps. sorry if it's confusing these are two

Question 62883: okay, i'm not very good at matrices...
[4 2]____[-6 0]
[5 1]*A= [-15 3]
(find matrix A)
please help i'll be very grateful!!
ps. sorry if it's confusing these are two 2x2 matrices ^^
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
[4 2]____[-6 0]
[5 1]*A= [-15 3]
---------------------
Assume A =[a b]
..........[c d]
------------------
Multiplying the matrices you get 4 equations:
---------------
First Set of equations:
1st: 4a+2c=-6
2nd: 5a+c=-15
Multiply 2nd by 2 to get:
5th: 10a+2c=-30
Subtract 1st from 5th to get:
6a=-24
a=-4
Substitute into 2nd to solve for "c", as follows:
5(-4)+c=-1
c=19
--------------
-----------
Second set of equations:
3rd: 4b+2d=0
4th: 5b+d=3
-----------
Multiply 4th by 2 to get:
6th: 10b+2d=6
Subtract 3rd from 6th to get:
6b=6
b=1
Substitute into 3rd to solve for "d":
4(1)+2d=0
d=-2
-------------
You now have a,b,c,d which are the elements of matrix A.
Cheers,
Stan H.

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