# Cramer's Rule

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• Dec 7th 2011, 05:22 PM
AlexWilson94
Cramer's Rule
Hello! I'm definitely struggling with Cramer's rule. We went over this part when I was out sick, and I'm not understanding how to do this. here's a problem:

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Thank you!
• Dec 7th 2011, 06:45 PM
pickslides
Re: Cramer's Rule
Your attachment has no application to cramer's rule.
• Dec 7th 2011, 06:52 PM
AlexWilson94
Re: Cramer's Rule
Oh my goodness. My bad, sorry about that.
Here it is:
http://oi42.tinypic.com/35b5bbr.jpg
Looks like some idiot decided to tag my other one.. Eh..
• Dec 8th 2011, 02:56 AM
HallsofIvy
Re: Cramer's Rule
Surely it is not all that hard to write:

"A gift shop is making a mixture of almonds, pecans, and peanuts which cost \$3.50 per pound, \$4.00 per pound,and \$2.00 per pound, respectively. The storekeeper wants to make 20 pounds of the mix to sell at \$2.70 per pound. The number of pounds of peanuts is to be three times the number of pounds of pecans. Find the number of pounds of each to be used in the mixture."

Okay, let x be the number of pounds of almonds, y the number of pounds of pecans, and z the number of pounds of peanuts used in the mixture.
The cost, in dollars, of the almonds used will be 3.5x, the cost of pecans used will be 4y, and the cost of peanuts used will be 2z.

"The store keeper want to make 20 pounds of the mix to sell at \$2.70 per pound".
x+ y+ z= 20, 3.5x+ 4y+ 2z= 2.7

"The number of pounds of peanuts is to be three times the number of pounds of pecans".
z= 3y which is the same as 0x- 3y+ 2z= 0.

You have the three equations
x+ y+ z= 20
3.5x+ 4y+ 2z= 2.7
0x- 3y+ 2z= 0

Now, what is "Cramer's rule"?