Desmos SAT Course: Solve Digital SAT Math

Foundations

Introduction to Desmos

A quick tour of the Desmos graphing calculator you get on the Digital SAT: graph an equation, zoom, scroll the plane, click a point to read its coordinates, and use a slider. Try each one on a live calculator.

Desmos is a built-in calculator on the Digital SAT

Every student gets the Desmos graphing calculator right inside the Digital SAT app, on the whole math section. It is the single biggest time saver on test day: instead of doing algebra by hand, you can graph the problem and read the answer straight off the screen.

This first lesson is a quick tour of the calculator itself. Once the five moves below feel natural, the rest of the course shows you exactly which one to reach for on each type of SAT math question.

Type an equation and it graphs itself

Type any equation into the list on the left and Desmos draws it on the right the instant you finish. You never have to plot points or rearrange for y by hand.

On the SAT: Turn a messy equation into a picture in a couple of seconds, then read the answer off the graph.

Typing y = x squared minus 3x minus 10 and watching it graph.

Zoom in and out

Scroll on the graph (or use the plus and minus buttons) to zoom. Zoom out when a graph shoots off the screen, zoom in when you need to read a point precisely.

On the SAT: Zoom out to find intercepts or a vertex that starts far away from the middle of the screen.

Zooming out and back in on a parabola.

Scroll around the graph plane

Click and drag anywhere on the grid to slide the view. Big graphs run right off the screen, so you scroll to follow the curve to the part you actually care about.

On the SAT: Chase a vertex or an intercept that sits way below or off to the side of the default view.

Dragging down to follow a steep parabola to its lowest point.

Click a point to read its exact coordinates

Hover or click a special point, like where two graphs cross, and Desmos labels it with its exact coordinates. That crossing point is the solution to the system.

On the SAT: Graph both sides of an equation, click where they meet, and read the solution instead of solving by hand.

Clicking the crossing point to reveal the solution (2, 3).

Add a slider for any unknown

Use a letter like a or k in your equation and Desmos offers to make it a slider. Drag the slider and the whole graph moves in real time so you can see what each value does.

On the SAT: Find the value of a constant that makes a line tangent, parallel, or pass through a certain point.

Dragging the slider a to reshape a parabola.

Try it yourselfSaved here, pick up where you left off

Type an equation like y=x^2-3x-10, then scroll to zoom and drag to move around. This is the real calculator you will use on the SAT.

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How to Use Desmos on the Digital SAT

The Digital SAT gives every student the Desmos graphing calculator, built into the Bluebook app, on the entire math section. Learning to use it well is one of the fastest ways to pick up SAT math points, because you can graph a problem and read the answer off the screen instead of solving it by hand. This interactive course, free to start, teaches you exactly which Desmos move to use on each type of SAT math question, with a live calculator in every lesson so you practice as you learn.

Start with the free introduction above. It is a quick tour of the calculator: graphing an equation, zooming, scrolling the graph plane, clicking a point to read its coordinates, and using a slider. From there, the course walks through 31 worked SAT question types, grouped into four skill sets. Want the quick hits instead? See the 15 Desmos SAT tricks distilled from these lessons.

Desmos SAT command cheat sheet

These are the inputs the whole course runs on. Each row links to a lesson that uses it on a real SAT question.

What you type	What it does	Lesson
`y = (left side) and y = (right side)`	Solves any equation: click the gray point where the graphs cross	Polynomial Multiplication
`The equation exactly as written, e.g. -12x + 14y = 36`	Graphs a line or curve without solving for y first	Exactly One Solution to a System
`A letter constant, e.g. h (then add slider)`	Drag the slider until the graph meets the question's condition	System of Linear Equations
`y1 ~ a^x1 + b (the tilde)`	Fits a model to a table and solves the unknown constants	Exponential Function Decay Rate
`distance((x1, y1), (x2, y2))`	Exact length between two points: radii, hypotenuses, segments	Circle Equation Constant Term
`f(x) = ... then f(0), f(12), ...`	Defines a function once and evaluates it anywhere	Yearly Decay Rate
`(1, 155) and (3, 285) as points`	Plots given points so you can see which choice passes through them	Table to Function
`Plain arithmetic, e.g. 1 - 0.35`	Evaluates ugly fractions and percent chains instantly	Mixture Problem with Percentages

Desmos SAT questions, answered

Can you use Desmos on the SAT?

Yes. The Digital SAT has the Desmos graphing calculator built into the Bluebook testing app, and you can use it on the entire math section, both modules. You do not install anything or bring your own device. It is right there next to every math question.

Is the SAT Desmos calculator the same as the free one online?

It is the same graphing engine, so everything you practice on desmos.com or in this course carries straight over to test day. The Bluebook version is trimmed down slightly, but the graphing, sliders, tables, and regressions you learn here all work the same on the real SAT.

How does Desmos help you solve SAT math questions?

Instead of doing algebra by hand, you turn the problem into a graph and read the answer off the screen. You can graph both sides of an equation and click where they cross, find a vertex or intercept, fit a line or curve to a table with a regression, or drag a slider to find the value of an unknown constant.

How do I solve an equation by graphing on the SAT?

Type the left side as y equals the left side, type the right side as its own y equals line, then click the gray point where the two graphs cross. The x-value at that crossing point is the solution. This works for linear, quadratic, absolute value, and many other equations.

Is this Desmos SAT course free?

The introduction is free for everyone. Create a free Cheetah Prep account to unlock more lessons, and go Pro to unlock all of the modules across graphing, systems, quadratics, and regressions.

Do I still need to know algebra if I use Desmos?

You need less of it. Desmos does not replace understanding the question, but it removes most of the by-hand solving. Many students who are shaky on algebra pick up a large number of math points just by learning which Desmos move fits each question type, which is exactly what this course teaches.

Can I use Desmos on both SAT math modules?

Yes. The calculator is available on Module 1 and Module 2 of the SAT math section. There is no no-calculator section on the Digital SAT, so you can reach for Desmos on any math question.