Digital SAT Math practice and Desmos strategy

Sample problem: linear equations

A phone plan charges a $20 monthly fee plus $0.05 per text. If a bill is $27.50, how many texts were sent?

Solution: 20 + 0.05t = 27.50, so 0.05t = 7.50 and t = 150 texts.

Sample problem: systems of equations

If 2x + y = 11 and x − y = 1, what is the value of x?

Solution: Add the equations to eliminate y: 3x = 12, so x = 4. In Desmos, graphing both lines and clicking the intersection gives (4, 3) just as quickly.

Sample problem: quadratics

What are the solutions to x² − 5x + 6 = 0?

Solution: Factor to (x − 2)(x − 3) = 0, so x = 2 or x = 3. Graphing y = x² − 5x + 6 in Desmos shows the same two x-intercepts.

When to use Desmos

Desmos is a powerful tool, but it is not always the fastest route.

• Use it for systems of equations, intersections, and finding zeros of functions.
• Use it to check algebra when time allows.
• Use sliders to explore how changing a constant affects a graph.
• Solve simple linear equations by hand; typing them takes longer.
• Practice in Desmos before test day so the interface is familiar.

Student-produced responses

For questions without answer choices, enter answers carefully. Fractions and decimals are both accepted within the stated rules, and negative answers are allowed. Re-read the question to confirm the units and the quantity being asked for before submitting.