Put the points in a table, add a regression, and read the equation of the line or curve of best fit. That replaces guessing a slope from a messy scatterplot. Desmos on the test is covered in Desmos on the ACT.
The clicks
Open a table. Enter x-values in one column and y-values in the next. Then add a regression. For a line, use y1 ~ mx1 + b. Desmos fills in m and b. For a quadratic fit, use y1 ~ ax1² + bx1 + c. The ~ is the regression operator, not an equals sign.
How to build the table itself is in Desmos tables. Reading a chart without a regression is in charts and tables on ACT Math.
Match the choice, do not over-round
The test's Desmos build still does basic regression. Features that are turned off are in what Desmos turns off. If the choices are equations, compare slope and intercept to m and b before you pick a “close” line.
The bottom line
Table, then y1 ~ mx1 + b. Read m and b. That is the line of best fit.
Start practicing
Start with a free diagnostic, then drill your weak spots with 15-question quizzes and track how you're doing across Reading, English, and Math. Compare plans whenever you're ready to go further.
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