Algebra Examples

Solve by Substitution x+y=8 , x-y=4
x+y=8 , x-y=4
Step 1
Subtract y from both sides of the equation.
x=8-y
x-y=4
Step 2
Replace all occurrences of x with 8-y in each equation.
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Step 2.1
Replace all occurrences of x in x-y=4 with 8-y.
(8-y)-y=4
x=8-y
Step 2.2
Simplify the left side.
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Step 2.2.1
Subtract y from -y.
8-2y=4
x=8-y
8-2y=4
x=8-y
8-2y=4
x=8-y
Step 3
Solve for y in 8-2y=4.
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Step 3.1
Move all terms not containing y to the right side of the equation.
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Step 3.1.1
Subtract 8 from both sides of the equation.
-2y=4-8
x=8-y
Step 3.1.2
Subtract 8 from 4.
-2y=-4
x=8-y
-2y=-4
x=8-y
Step 3.2
Divide each term in -2y=-4 by -2 and simplify.
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Step 3.2.1
Divide each term in -2y=-4 by -2.
-2y-2=-4-2
x=8-y
Step 3.2.2
Simplify the left side.
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Step 3.2.2.1
Cancel the common factor of -2.
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Step 3.2.2.1.1
Cancel the common factor.
-2y-2=-4-2
x=8-y
Step 3.2.2.1.2
Divide y by 1.
y=-4-2
x=8-y
y=-4-2
x=8-y
y=-4-2
x=8-y
Step 3.2.3
Simplify the right side.
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Step 3.2.3.1
Divide -4 by -2.
y=2
x=8-y
y=2
x=8-y
y=2
x=8-y
y=2
x=8-y
Step 4
Replace all occurrences of y with 2 in each equation.
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Step 4.1
Replace all occurrences of y in x=8-y with 2.
x=8-(2)
y=2
Step 4.2
Simplify the right side.
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Step 4.2.1
Simplify 8-(2).
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Step 4.2.1.1
Multiply -1 by 2.
x=8-2
y=2
Step 4.2.1.2
Subtract 2 from 8.
x=6
y=2
x=6
y=2
x=6
y=2
x=6
y=2
Step 5
The solution to the system is the complete set of ordered pairs that are valid solutions.
(6,2)
Step 6
The result can be shown in multiple forms.
Point Form:
(6,2)
Equation Form:
x=6,y=2
Step 7
image of graph
x+y=8,x-y=4
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