Question 925933
x = janet age now
y = julie age now
z = brother age now
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x + y + z = 55
x = y + 3
z = y - 8
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put the system of linear equations into standard form
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x + y + z = 55
x - y = 3
y - z = 8
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solution by matrix method:
x = janet age now = 23
y = julie age now = 20
z = brother age now = 12
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by elimination:
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x + y + z = 55
(x - y = 3)(-1)
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x + y + z = 55
-x + y = -3
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add the above two equations:
2y + z = 52
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2y + z = 52
y - z = 8
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add the above two equations:
3y = 60
y = 20
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-x + y = -3
-x + 20 = -3
-x = -23
x = 23
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y - z = 8
20 - z = 8
-z = -12
z = 12
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solution by elimination matches solution by matrix method:
x = janet age now = 23
y = julie age now = 20
z = brother age now = 12
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