SOLUTION: solving using matrices, fred has nickels dimes and quarters worth $5.00 in his pocket. the number of quarters is 3 times the number of nickels. how many of each type of coin does h

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Question 802284: solving using matrices, fred has nickels dimes and quarters worth $5.00 in his pocket. the number of quarters is 3 times the number of nickels. how many of each type of coin does he have if there are 30 coins in all!
I know how to solve them in my calculator TI-84! But with this problem I have no idea how to set it up! Once I know how to set it up I can plug it into my calculator, but this one is just weird!
I have gotten this far
N+d+q=5.00

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


You are getting yourself into trouble right off the bat. Your claim is that:



So your claim is that the number of nickels plus the number of dimes plus the number of quarters is the same as the value of the money he has. Not even close. The number of nickels plus the number of dimes plus the number of quarters is the NUMBER of coins he has, in this case, 30.



Now you need a VALUE equation. The VALUE of the nickels plus the VALUE of the dimes plus the VALUE of the quarters is the same as the VALUE of the money he has.



Then you are also given that:



which you can rearrange thusly:



Now, you can use these three equations and set up a 3X4 augmented matrix, or you can substitute for in the first two equations, simplify, and then solve the much simpler 2X2 system.

John

Egw to Beta kai to Sigma
My calculator said it, I believe it, that settles it
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