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David Cohen Textbook Questions.
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a+b=7
-2b+c=-9
9a-2c=29
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a+b=7
a=7-b.....1)
9a-2c=29
a=(29+2c)/9.....2)
from 1) and 2) we have
7-b=(29+2c)/9
b= 7-(29+2c)/9
b = 34/9 - (2 c)/9....3)
-2b+c=-9
9+c=2b
b=(9+c)/2..........4)
from 3) and 4) we have
34/9 - (2 c)/9=(9+c)/2
-(13 c)/18 - 13/18 = 0
c=-1
go to
b=(9+c)/2..........4), substitute c
b=(9-1)/2
b=4
go to
a=7-b.....1), substitute b
a=7-4
a=3
solutions:
a = 3, b = 4, c = -1