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solve the system
7x - y = 31, (1)
2x + 3y = -1. (2)
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From (1), express y = 31-7x and substitute it into (2). You will get
2x + 3*(31-7x) = -1.
Simplify and solve for x.
It is called "the Substitution method".
On solving linear systems of algebraic equations in two unknowns seee 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
- Solving word problems using linear systems of two equations in two unknowns
in this site.