Question 624841
method of usbstitution
1:a=5-2b
5a+2b=1
Sub for a in the 2nd eqn
5(5-2b) + 2b = 1
25-10b + 2b = 1
-8b = -24
b = 3
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a = 5-2b
a = -1
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2: 2m+n=0
m+2n=3
Solve either eqn for either m or n:
m+2n=3 --> m = 3-2n
Then it's the same as #1
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3 to 7 are the same as #2
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3: x+y=4
2x-y=5
4: y-2x=1
3x-4y=1
5: a-2b=9
2a+3b=4
6: x+2y=7
3x-2y=3
7: 2a+b=9
3a-2b=11