.
solve by addition method.
8x-3y=18
4x+5y=-4
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8x - 3y = 18 (1)
4x + 5y = -4 (2)
Multiply equation (2) by (-2) (both sides). Keep equation (1) as is. You get an equivalent system
8x - 3y = 18 (1')
-8x - 10y = 8 (2')
Now add equations (1') and (2'). The terms "8x" will cancel each other, and you will get a single equation for the unique unknown y:
-3y + (-10y) = 18 + 8, or
-13y = 26. It implies y = = -2.
Next substitute the found value of y into equation (1). You will get
8x - 3*(-2) = 18 ====> 8x = 18 + 3*(-2) = 12 ====> x = = .
Answer. x = , y = -2.
Check the answer on your own.
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Notice that the standard and official name of this method is "the Elimination method".
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On solving systems of linear equations in two unknowns see the lessons
- Solution of a linear system of two equations in two unknowns by the Substitution method
- Solution of a linear system of two equations in two unknowns by the Elimination method
- Solution of a linear system of two equations in two unknowns using determinant
- Geometric interpretation of a 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".
Save the link to this online textbook together with its description
Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson
to your archive and use it when it is needed.