Discriminant and number of roots
Quadratics and polynomials · Stage 3
Recognize the pattern
The sign of b²−4ac tells the number of distinct real roots.
Useful ruleb²−4ac
Build on: ADM-04
Try it before reading the solution
How many real roots does x² − 4x + 4 = 0 have?
This teaching example is original and is not an official SAT question.
Reasoning
The discriminant is 16−16=0, so the graph touches the x-axis once.
AnswerOne distinct real root
03 · Next step
See membership →Ready for adaptive practice
Practice questions remain in English, as on the SAT.