Question 828349: Mike is 5 years less than three times as old as his sister. Next year he will be twice as old as she will be. How old is each? Answer by TimothyLamb(4379) (Show Source):
You can put this solution on YOUR website! ---
x = Mike
y = sister
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x = 3y - 5
x + 1 = 2(y + 1)
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put the system of linear equations into standard form:
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x - 3y = -5
x - 2y = 1
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solution:
x = Mike = 13
y = sister = 6
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system matrix
1 -3
1 -2
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inverse of system matrix
-2 3
-1 1
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determinant of system matrix = 1
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