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Da VIP Academy / GED / Math / Algebra & Functions

Functions & Graphs

Use function notation, find slope, and interpret linear graphs.

Practice this skillAll Math skills

How it works

Function notation

f(x) = 2x + 5 is a rule. f(−3) means substitute −3: 2(−3) + 5 = −1.

Slope is rise over run

Between (2, 3) and (6, 11): slope = (11 − 3) ÷ (6 − 2) = 8 ÷ 4 = 2. In y = mx + b, m is slope and b is the y-intercept.

Worked examples

  1. Find the slope through (2, 3) and (6, 11).

    1. Rise = 11 − 3 = 8.
    2. Run = 6 − 2 = 4.
    3. Slope = 2.

Words to know

Slope
The steepness of a line: change in y over change in x.
y-intercept
Where the line crosses the y-axis.

Test-day tips

  • • In a real-world graph, slope is a rate (dollars per hour, miles per gallon).
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