子主题
Linear equations in one variable
Solving equations of the form ax + b = c, including equations with fractions and variables on both sides.
Linear equations in two variables
Slope, intercepts, slope-intercept form, point-slope form, standard form, and contextual interpretation.
Systems of two linear equations
Substitution and elimination methods. Recognizing no-solution and infinite-solution cases.
Linear inequalities
Solving and graphing inequalities in one and two variables. Systems of linear inequalities.
Interpreting linear functions
Reading slope and intercept from context, identifying linear vs. non-linear models from tables and graphs.
关键公式
y = mx + b (slope-intercept form)y − y₁ = m(x − x₁) (point-slope form)m = (y₂ − y₁) / (x₂ − x₁) (slope)Ax + By = C (standard form)New = Original × (1 ± r) (percent change)应试技巧
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Always check: does the question want the value of x or an expression like 2x + 1?
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When given a word problem, define your variable before writing the equation.
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For systems, elimination is often faster than substitution when coefficients align.
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On the SAT, "no solution" means parallel lines; "infinite solutions" means the same line.