SAT Linear Equations in Two Variables study notes

A two-variable equation describes many ordered pairs. To test one, replace x and y with the coordinates and see whether the two sides match. To isolate a variable, treat everything attached to it as one expression until the final division.

Worked example

For 3x + 2y = 19, what is y when x = 3?

Substitute 3 for x: 9 + 2y = 19. Subtract 9, then divide by 2. The pair (3, 5) lies on the line.

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