Every digital SAT includes a Desmos graphing calculator built into Bluebook. Most students use it like a four-function calculator — which is like using a car to push a shopping cart. Here are the 8 Desmos moves that reliably save 20+ seconds per question, ranked by how often they show up.
1. Type the whole equation, let Desmos graph it
When you see "In the xy-plane, the graph of y = 2x² − 5x + 3 intersects the x-axis at which of the following?" — don't factor. Type the equation into Desmos. It shows you the roots as labeled points. Click them. Done in 6 seconds.
2. Graph systems of equations together
Any "find the solution to this system" question — type both equations on separate lines. Desmos draws the intersection and labels the coordinates. You never touched a substitution.
3. Use variable sliders for "for what value of k" questions
When the question is "for what value of k does the system have exactly one solution," write the equations with k in them. Desmos prompts you to add a slider for k. Drag the slider, watch the graphs. When the two lines become tangent, read off the k value.
4. Use regression for "line of best fit" questions
Type your data as a table — the syntax is a two-column table with x and y. Then on a new line type y1 ~ mx1 + b. Desmos runs a linear regression and spits out m and b. Works for exponential and quadratic regressions too: y1 ~ a*b^x1 or y1 ~ a*x1² + b*x1 + c.
5. Solve inequalities graphically
For "which inequality describes the shaded region," type the candidate inequalities directly (Desmos supports <, >, ≤, ≥). The shaded region appears on the graph — match it visually.
6. Use named functions to keep your workspace clean
Write f(x) = 3x² − 2x + 1 on one line. Now you can type f(2), f(-5), f(0) on subsequent lines and Desmos evaluates instantly. This is faster than retyping the expression each time for multi-part questions.
7. Circle equations — just type them
A circle with equation (x − 3)² + (y + 2)² = 16 — just type it. Desmos graphs the circle with center and radius labeled when you hover. Faster than completing the square by hand.
8. The zero check for "which statement must be true"
For questions that ask which of several statements must be true about a function — graph the function, then graph the equation you're testing. If the graphs overlap, it's true. If they're identical, the statement is an identity. This is massively faster than algebraic manipulation.
