The Sign of a Function (HSC SSCE Mathematics Advanced): Flashcards

Curve is above the $x$-axis

Endpoint is included (like $leq$ or $geq$)

Endpoint not included (like $<$ or $>$)

$\infty$ is not a number, can't be included

Union; combines intervals (corresponds to 'or')

Only at zeroes or discontinuities

Value where $f(x) = 0$ (curve crosses/touches $x$-axis)

No; curve touches but doesn't cross $x$-axis

Numerator for zeroes, denominator for discontinuities

One; sign is constant between critical points