Linear equations in two variables

강의 소개

Linear equations in two variables, Ax + By = C: reading the slope and both intercepts, writing the equation of a line through two points, building an equation from a word problem, and interpreting each coefficient in context.

On the Digital SAT, linear equations in two variables belong to the Algebra domain and are among the most frequent math questions. You may get an equation in standard form and be asked for its slope or an intercept, two points and a request for the line through them, or a story about two items with different prices followed by "which equation represents this situation" or "what does this coefficient mean".

Most mistakes happen while reading, not while calculating: using A/B instead of −A/B, swapping the x- and y-intercepts, or attaching a price to the wrong variable. This lesson gives three quick readings of Ax + By = C, a reliable way to write a line from two points, a simple rule for interpreting coefficients in context, and point-testing and Desmos checks for the answer choices. It ends with 6 self-graded practice questions, each with a full explanation.