SAT and ACT math terms · SAT Math, ACT Math
Slope-intercept form
Slope-intercept form: The form y = mx + b of a linear equation, where m is the slope and b is the y-intercept.
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What it means
Slope-intercept form makes a line's key features visible. The y-intercept b is the value of y when x = 0, often the starting value in a word problem. Other forms include point-slope form, y − y₁ = m(x − x₁), and standard form, Ax + By = C.
To convert standard form to slope-intercept form, solve for y.
Example
A gym charges a $25 sign-up fee plus $15 per month: y = 15x + 25. The slope 15 is the monthly cost and the intercept 25 is the fee.
On the exam
Expect to match an equation to a context or graph, or to identify what m or b means in a scenario.