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| Question 930373:  I have posted about this problem once and it was said to not be able to be solved but it is to be solved because it is a specific question I need help with. please and thank you if you can help me!!
 Create a trail mix with three ingredients; peanuts, fruit, and cashews. The cost per pound of peanuts are $3, fruit $6, and cashews $3. One ingredient must have twice the weight of other two. (that part can be made up, I was not sure what to make those numbers). using systems of equations and or matrices how many pounds of each should be used to make a 140 lb mix at 6$ a pound?
 Answer by TimothyLamb(4379)
      (Show Source): 
You can put this solution on YOUR website! x = pounds of peanuts y = pounds of fruit
 z = pounds of cashews
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 "one ingredient must have twice the weight of other two" ...
 arbitrarily choose the weight of peanuts to be twice the sum of the weights of fruit and cashews:
 x = 2(y + z)
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 sum of weights:
 x + y + z = 140
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 sum of costs:
 3x + 6y + 3z = 6*140
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 put the system of linear equations into standard form
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 x = 2y + 2z
 x + y + z = 140
 3x + 6y + 3z = 840
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 x - 2y - 2z = 0
 x + y + z = 140
 3x + 6y + 3z = 840
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 copy and paste the above standard form linear equations in to this solver:
 https://sooeet.com/math/system-of-linear-equations-solver.php
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 solution:
 x = pounds of peanuts = 93.333333
 y = pounds of fruit = 140
 z = pounds of cashews = -93.333333
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 as you can see, pounds of cashews comes out negative, which is impossible in real life.
 this means that the problem statement is fundamentally incorrect.
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 Solve and graph linear equations:
 https://sooeet.com/math/linear-equation-solver.php
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 Solve quadratic equations, quadratic formula:
 https://sooeet.com/math/quadratic-formula-solver.php
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 Solve systems of linear equations up to 6-equations 6-variables:
 https://sooeet.com/math/system-of-linear-equations-solver.php
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