What formulas are most important for application of derivatives Class 12?
Key formulas include $f'(x) > 0$ for increasing, $f'(x) < 0$ for decreasing, $f'(x) = 0$ and $f''(x) > 0$ for minima, $f'(x) = 0$ and $f''(x) < 0$ for maxima, and $f''(x) = 0$ for points of inflection.