Desmos I
The basicsTyping equations in exactly as written, reading solutions off the graph, systems of equations, and finding a vertex or an intercept.
How to Use Desmos on the SAT
Desmos is the most important tool on the Math SAT. The more you use it, the higher your score. Here's how.
These are two of my Desmos lessons, free and with no account. You use the real calculator, and the lesson checks your graph before you go on.
Desmos II
The toolsSliders, functions built from other functions, regressions, and absolute value.
Start Desmos II
Best after Desmos I.
Desmos cheat sheet
Pick the kind of question. The second column is exactly what to type into Desmos.
Solving equations
The questionType thisLook forAnswer
Solve for x
7p2 − 38p − 24 = 0
What is the positive solution to the given equation?
Desmos I
Type this
7x2 − 38x − 24 = 0
Look for
Answer
p = 6
How many solutions
37(x3 + 125)(x4 − 16) = 0
How many distinct real solutions does the given equation have?
Desmos I
Type this
37(x3 + 125)(x4 − 16) = 0
Look for
Answer
3
Systems of equations
y = 9x − 18 y = 36
What is the solution (x, y) to the given system of equations?
Desmos I
Type this
y = 9x − 18
y = 36
Look for
Answer
(6, 36)
Absolute value
|x − 7| + 32 = 51
What is the sum of the solutions to the given equation?
Desmos II
Type this
|x − 7| + 32 = 51
Look for
Answer
−12 + 26 = 14
Functions
The questionType thisLook forAnswer
Minimum or maximum
f(x) = (x − 8)(x + 17)
For what value of x does f(x) reach its minimum?
Desmos I
Type this
y = (x − 8)(x + 17)
Look for
Answer
x = −4.5
One function built from another
f(x) = 3x2 + 42x + 155
The function g is defined by g(x) = f(x + 4). For what value of x does g(x) reach its minimum?
Desmos II
Type this
f(x) = 3x2 + 42x + 155
g(x) = f(x + 4)
Look for
Answer
x = −11
Missing pieces
The questionType thisLook forAnswer
A missing constant
3x + 21 = a(x + 7)
In the given equation, a is a constant. If the equation has infinitely many solutions, what is the value of a?
Desmos II
Type this
y = 3x + 21
y = a(x + 7)
Look for
Answer
a = 3
The equation from a table
| x | 1 | 2 |
|---|---|---|
| y | 11 | 15 |
Which equation represents the linear relationship between x and y?
Desmos II
Type this
| x1 | y1 |
|---|---|
| 1 | 11 |
| 2 | 15 |
| 3 | 19 |
y1 ~ mx1 + b
Look for
Answer
y = 4x + 7
Questions
Can you use Desmos on the SAT?
Yes. The digital SAT has the Desmos graphing calculator built into Bluebook, and you can use it on the entire Math section. You're also allowed to bring your own approved calculator, but I'd learn Desmos either way.
Is the SAT's Desmos the same as desmos.com?
Nearly. The SAT version turns off images, folders, and notes, none of which you need for SAT math. Everything you'd use is there, and it's the same calculator my lessons use.
Should I use Desmos on every math question?
Not every one, but more than you'd think. In my experience, the math section has gotten harder since Desmos was built into the test, and the students who are fluent with it handle the hardest questions far better than the ones who aren't.
Do I need an account for the lessons?
No. Both lessons are free and work without an account. If you want to save your progress, or try the drills that go with them, you can create an account and use everything free for two weeks.
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