| 释义 |
Rolle's theorem
Rolle's theorem R0289300 (rôlz, rōlz)n. A theorem stating that if a curve is continuous, has two x-intercepts, and has a tangent at every point between the intercepts, at least one of these tangents is parallel to the x-axis. [After Michel Rolle (1652-1719), French mathematician.]
Rolle's Theorem
Rolle's theorem[′rȯlz ‚thir·əm] (mathematics) If a function ƒ(x) is continuous on the closed interval [a, b ] and differentiable on the open interval (a, b) and if ƒ(a) = ƒ(b), then there exists x0, a <>x0<>b, such that ƒ′(x 0)=0. Rolle’s Theorem a theorem of mathematical analysis first stated by M. Rolle in 1690. According to this theorem, if the function f(x) is continuous on the closed interval [a, b], has a definite derivative within the interval, and takes on the equal values f(a) = f(b) at the ends of the interval, then the function’s Figure 1
derivative f’(x) vanishes at least once in the interval (a, b)—that is, there exists a c, a < c < b, such that f’(c) = 0. A corollary of the theorem provides that the derivative of a function has at least one zero between two successive zeros of the function. Geometrically, Rolle’s theorem is self-evident (see Figure 1). (See alsoDIFFERENTIAL CALCULUS.) |