Use Desmos with a purpose.
The SAT includes a graphing calculator throughout Math. Practice using it to confirm structure, not replace understanding.
Graph both sides
For a system, enter each equation and inspect the intersection. For f(x) = k, graph y = f(x) and y = k. Remember the question may ask for a sum or a y-value.
Read roots and vertices
A root is an x-intercept; a minimum or maximum is a vertex. Choose the feature the question actually requests.
Check your window
A graph outside the visible window has not disappeared. Zoom out or adjust bounds, and verify values by substitution when possible.
Know when paper is faster
Simple linear equations and recognizable factoring patterns often take less time by hand. Practice both approaches in Bluebook so the interface feels familiar.
For y = 2x + 1 and y = −x + 10, the graphs meet at (3, 7). If asked for x + y, enter 10—not 3 or 7.
Format reference: College Board’s SAT structure. Try the tools in Bluebook practice.