How to Use Desmos Effectively for the SAT Math Section
- James Quarrington
- Mar 25
- 3 min read
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The SAT Math section tests a mix of algebra, problem-solving, data analysis, and geometry. While a traditional calculator can be useful, the Desmos graphing calculator, provided on the SAT’s digital version, is a game-changer—if you know how to use it effectively.
In this guide, I’ll show you how to maximize Desmos to save time, avoid mistakes, and tackle tricky questions with confidence.
Why Use Desmos on the SAT?
Desmos isn’t just a calculator—it’s a visual problem-solving tool. Unlike handheld calculators, it allows you to:
✅ Quickly graph equations to identify key points (intercepts, intersections, and trends).
✅ Check algebraic work without manually solving everything.
✅ Spot patterns in tables and equations that would take longer to recognize by hand.
✅ Save time on word problems by testing values and exploring relationships visually.
Many students don’t take full advantage of Desmos on test day. Here’s how you can use it to boost your score.
1. Graph Equations to Find Solutions Instantly
Instead of solving for x algebraically, Desmos lets you graph and visually locate solutions.
Example: Solve for x
If 3x – 7 = 2x + 5, what is x?
Algebraic Approach
Subtract 2x: x – 7 = 5
Add 7: x = 12
Desmos Approach
Graph y = 3x – 7
Graph y = 2x + 5
The x-value of the intersection is the answer: x = 12
Desmos helps confirm your work or bypass algebra altogether in seconds.
2. Use Tables to Test Values Quickly
Some SAT questions involve functions and sequences. Instead of manually substituting values, Desmos lets you create tables to test different inputs.
Example: Function Evaluation
If f(x) = 2x² – 3x + 4, what is f(5)?
Steps on Desmos:
Type f(x) = 2x² – 3x + 4
Click the table icon
Enter x = 5
The output (y-value) gives the answer, 34
This is much faster than substituting in numbers by hand.
3. Find Intersections for System of Equations
The SAT often asks about systems of equations. Instead of solving by substitution or elimination, graph both equations in Desmos and find the intersection.
Example: System of Equations
2x + 3y = 12
4x – y = 5
Steps on Desmos:
Type both equations into Desmos.
Find the point where they intersect (x=3, y=3).
This method is quick and reduces calculation errors.
4. Check Answers Using Desmos Graphs
A powerful Desmos trick is graphing answer choices to see which one fits. This works especially well for quadratic and exponential functions.
Instead of solving manually, just enter each answer choice into Desmos and see which one matches the given graph. This eliminates guesswork and helps answer questions quickly!.
5. Solve Inequalities & Absolute Value Questions
Inequalities and absolute values can be tricky to solve algebraically, but Desmos shows the solution visually.
Example: Solve for x
If |x – 4| > 2, what values satisfy x?
Steps on Desmos:
Graph y = |x – 4|
Graph y = 2
Identify where y-values are greater than 2
The solution is x < 2 or x > 6—which you can see clearly on the graph.
Final Desmos Tips for the SAT
✅ Use it for verification – Solve algebraically, then graph to check. ✅ Get comfortable with tables – They speed up function-related questions. ✅ Practice before test day – Don’t wait until the exam to explore Desmos. ✅ Use it wisely – Don’t rely on it for everything; some questions are faster by hand.
Mastering Desmos strategies can shave minutes off your test time and improve accuracy. Make it part of your SAT prep routine, and you’ll gain a major edge on test day!
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