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Question 1071223: Solve the following pairs of simultaneous equations:
X+2y=3,X-2y=3
Y=2×-1,Y=3x-2
2y=6x-4,Y=3x-2
Found 2 solutions by josgarithmetic, ikleyn: Answer by josgarithmetic(39617) (Show Source): Answer by ikleyn(52787) (Show Source):
You can put this solution on YOUR website! .
Solve the following pairs of simultaneous equations:
X+2y=3,X-2y=3
Y=2×-1,Y=3x-2
2y=6x-4,Y=3x-2
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1.
x + 2y = 3,
x - 2y = 3.
Add the two equations (both sides). The terms with "y" will cancel, and you will get
2x = 6, which implies x = 3.
Now, substitute the found value x= 3 into the first equation. You will get
3 + 2y = 3 ---> 2y = 0 ---> y= 0.
Answer. The solution is x= 3, y= 0.
The method I applied is called the Elimination method.
2.
y = 2x - 1,
y = 3x - 2.
Since the left sides are identical, the right sides are equal:
2x - 1 = 3x - 2 ---> -1 + 2 = 3x - 2x ---> 1 = x ---> x = 1.
Now, substitute the found value x= 1 into the first equation. You will get
y = 2*1 - 1 = 2 - 1 = 1.
Answer. The solution is x= 1, y= 1.
3.
2y = 6x - 4,
y = 3x - 2.
In the first equation, divide both sides by 2. You will get an equivalent equation
y = 3x - 4.
Compare it with the second equation.
You see that they are identical.
So, your system is actually one equation for two unknowns, since the second equation is equivalent to the first one.
Geometrically, these two equations represent one straight line.
The original system has infinitely many solutions.
On solving systems of two linear equations in two unknowns see the lessons
- Solution of the linear system of two equations in two unknowns by the Substitution method
- Solution of the linear system of two equations in two unknowns by the Elimination method
- Solution of the linear system of two equations in two unknowns using determinant
- Geometric interpretation of the linear system of two equations in two unknowns
in this site.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this online textbook under the topic "Systems of two linear equations in two unknowns".
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