Question

Use the matrix method to solve the system of equations.
A man has 30 coins, which are all dimes or nickels. Their combined value is $2.10. How many coins of each kind does he have? Let x = the number of nickels. Let y = the number of dimes. Set up two linear equations and use the matrix method to solve.
Number of nickels =___
Number of dimes =___

Answer 1

x + y = 30
0.05x + 0.1y = 2.1
Find the determinant of: \[\left[\begin{matrix}1 & 1 \\ 0.05& 0.1\end{matrix}\right]\]
This is the system determinant.
Find the determinant of: \[\left[\begin{matrix}30 & 1 \\ 2.1 & 0.1\end{matrix}\right]\]
This is the x determinant.
Find the determinant of: \[\left[\begin{matrix}1 & 30 \\ 0.05 & 2.1\end{matrix}\right]\]
THis is the y determinant.
Now divide the x determinant by the system determinant to get the x-value.
Then divide the y determinant by the system determinant to get the y-value.

Answer 2

I`m sorry but how do yo divide the system determinant?

Answer 3

*you

Answer 4

Do you know how to find the system determinant?

Answer 5

no :S

Answer 6

1(0.1) - 1(0.05) = 0.05
You multiply diagonally and then subtract. It's diagonally down first, and then subtract by the upward diagonal.

Answer 7

ad - bc

Answer 8

Got it! so the number of nickels would be 18 and number of dimes would be dimes would be 12?

Answer 9

Yupeee!

Answer 10

Yes! :)

Answer 11

okay could you help me how to create the equation for this problem?
Use the matrix method to solve the system of equations.
Investor Company loaned out a total of $36,000, part at 6% interest and part at 9% interest. They reported that the annual earnings from both investments were the same amount that would have been earned by the total loan if it had been invested at 8%. Find the amount loaned at each rate. Use matrix methods.
Amount loaned at 6% = $_____
Amount loaned at 9% = $_____
I`m sorry I dont get how to do this one :S @Calcmathlete

Answer 12

Would you open the new post per question :)

Answer 13

Done :P

Answer 14

http://openstudy.com/study#/updates/4fd01e70e4b0e0466317cd94