Solve systems of two linear equations exactly and approximately using algebraic and graphical methods.
Solve a system by isolating a variable first, then substituting
Problem
Solve the system by isolating a variable first, then substituting: \(x~+~y~=~9\), \(2x~-~y~=~6\).
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What this problem is really about
Substitution begins by isolating the variable whose coefficient makes the rearrangement simplest. We’ll create an equivalent expression from one equation, place that whole expression in parentheses when replacing the variable in the other, and distribute any outside sign carefully. After solving and back-substituting, both original equations must agree with the resulting ordered pair.
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