SOLUTION: Using the elimination process how do you find -8x+4y=-7 4x-2y=-1 3x+7y=10 5x=7-2y

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Question 548422: Using the elimination process how do you find
-8x+4y=-7
4x-2y=-1


3x+7y=10
5x=7-2y

Answer by Maths68(1474) About Me  (Show Source):
You can put this solution on YOUR website!
-8x%2B4y=-7..........(1)
4x-2y=-1...........(2)
Multiply by -2 both sides of equation (2)
-8x%2B4y=2...........(3)
LHS of equation (1) and (3) are same but RHS of both equation is different. It means that values of x and y for both equation are different. Therefore it is impossible to know the value of x and y by solving these two equations.

3x%2B7y=10.............(1)
5x=7-2y
5x%2B2y=7..............(2)
Multiply (1) by 5 and (2) by 3
15x%2B35y=50.............(3)
15x%2B6y=21..............(4)
Subtract (4) from (3)
15x%2B35y=50.............(3)
-15x-6y=-21..............(4)
----------------
29y=29
29y%2F29=29
cross%2829%29y%2Fcross%2829%29=cross%2829%29%2Fcross%2829%29
y=1
Put the value of y in (1)
3x%2B7y=10.............(1)
3x%2B7%281%29=10
3x%2B7=10
3x=10-7
3x=3
3x%2F3=3%2F3
x=1
(x,y)=(1, 1)

Check
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Put the values of x and y in (1)
3x%2B7y=10.............(1)
3%281%29%2B7%281%29=10
3%2B7=10
10=10
Put the values of x and y in (2)
5x%2B2y=7..............(2)
5%281%29%2B2%281%29=7
5%2B2=7
7=7