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▼❛t❤ ✶✸✷✿ ❉✐s❝✉ss✐♦♥ ❙❡ss✐♦♥✿ ❲❡❡❦ 3 ❉✐r❡❝t✐♦♥s✿ ■♥ ❣r♦✉♣s ♦❢ 3✲4 st✉❞❡♥ts✱ ✇♦r❦ t❤❡ ♣r♦❜❧❡♠s ♦♥ t❤❡ ❢♦❧❧♦✇✐♥❣ ♣❛❣❡✳ ❇❡❧♦✇✱ ❧✐st t❤❡ ♠❡♠❜❡rs ♦❢ ②♦✉r ❣r♦✉♣ ❛♥❞ ②♦✉r ❛♥s✇❡rs t♦ t❤❡ s♣❡❝✐✜❡❞ q✉❡st✐♦♥s✳ ❚✉r♥ t❤✐s ♣❛♣❡r ✐♥ ❛t t❤❡ ❡♥❞ ♦❢ ❝❧❛ss✳ ❨♦✉ ❞♦ ♥♦t ♥❡❡❞ t♦ t✉r♥ ✐♥ t❤❡ q✉❡st✐♦♥ ♣❛❣❡ ♦r ②♦✉r ✇♦r❦✳ ❆❞❞✐t✐♦♥❛❧ ■♥str✉❝t✐♦♥s✿ ❲❡✬❧❧ s♣❡♥❞ s♦♠❡ ♦❢ t❤❡ t✐♠❡ ♦♥ t❤✐s ✇♦r❦s❤❡❡t✱ ❛♥❞ s♦♠❡ ♦❢ t❤❡ t✐♠❡ r❡✈✐❡✇✐♥❣ ❢♦r t❤❡ ❡①❛♠✳ ■t ✐s ♦❦❛② ✐❢ ②♦✉ ❞♦ ♥♦t ❝♦♠♣❧❡t❡❧② ✜♥✐s❤ ❛❧❧ ♦❢ t❤❡ ♣r♦❜❧❡♠s✳ ❆❧s♦✱ ❡❛❝❤ ❣r♦✉♣ ♠❡♠❜❡r s❤♦✉❧❞ ✇♦r❦ t❤r♦✉❣❤ ❡❛❝❤ ♣r♦❜❧❡♠✱ ❛s s✐♠✐❧❛r ♣r♦❜❧❡♠s ♠❛② ❛♣♣❡❛r ♦♥ t❤❡ ❡①❛♠✳ ❙❝♦r✐♥❣✿ ❈♦rr❡❝t ❛♥s✇❡rs ●r❛❞❡ ✵✕✶ ✵✪ ✷✕✸ ✽✵✪ ✹✕✺ ✶✵✵✪ ●r♦✉♣ ▼❡♠❜❡rs✿ ✺✳✸✿ ❋✉♥❞❛♠❡♥t❛❧ ❚❤❡♦r❡♠ ♦❢ ❈❛❧❝✉❧✉s✳ ✭✶✮ ✭❛✮ F′(x) = ✭❜✮ G′(x) = ✭✷✮ F(x) = ✭✸✮ ✭❛✮ ❙t❛t❡ t❤❡ ❝r✐t✐❝❛❧ ♣♦✐♥t✭s✮ ❛♥❞ ✇❤❡t❤❡r F ❤❛s ❛ ❧♦❝❛❧ ♠❛①✱ ❧♦❝❛❧ ♠✐♥✱ ♦r ♥❡✐t❤❡r ❛t ❡❛❝❤ ♦♥❡✿ ✭❜✮ ❙t❛t❡ t❤❡ ✐♥✢❡❝t✐♦♥ ♣♦✐♥t✭s✮ ❛♥❞ ❤♦✇ t❤❡ ❝♦♥❝❛✈✐t② ♦❢ F ❝❤❛♥❣❡s ❛t ❡❛❝❤ ♦♥❡✿ ▼❛t❤ ✶✸✷ ❉✐s❝✉ss✐♦♥ ❙❡ss✐♦♥✿ ❲❡❡❦ ✷ ✺✳✸✿ ❋✉♥❞❛♠❡♥t❛❧ ❚❤❡♦r❡♠ ♦❢ ❈❛❧❝✉❧✉s✳ ✭✶✮ ❯s✐♥❣ t❤❡ ❋✉♥❞❛♠❡♥t❛❧ ❚❤❡♦r❡♠ ♦❢ ❈❛❧❝✉❧✉s✱ ❝♦♠♣✉t❡ t❤❡ ❞❡r✐✈❛t✐✈❡s ♦❢ t❤❡ ❢♦❧❧♦✇✐♥❣ ❢✉♥❝t✐♦♥s✿ Z x2 e x+1 ✭❛✮ F(x) = x−1dx 2 ❙♦❧✉t✐♦♥✿ ▲❡t H(x) ❜❡ ❛♥ ❛♥t✐❞❡r✐✈❛t✐✈❡ ♦❢ x+1✱ s♦ H′(x) = x+1✳ ❚❤❡♥ x−1 x−1 Z ex2 x+1 x2 2 x−1dx=H(e )−H(2), Z ex2 d x+1 2 2 ′ x x dx 2 x−1dx=H(e )· e (2x)−0 2 x e +1 2 x = 2 · 2xe . x e −1 ✭❜✮ G(x) = Z x2 ln(x+3)dx. cosx ❙♦❧✉t✐♦♥✿ ▲❡t K(x) ❜❡ ❛♥ ❛♥t✐❞❡r✐✈❛t✐✈❡ ♦❢ ln(x + 3)✱ s♦ K′(x) = ln(x + 3)✳ ❚❤❡♥ Z 2 x 2 cosx ln(x + 3) = K(x ) −K(cosx), Z 2 d x ′ 2 ′ dx cosxln(x+3) = K (x )·(2x)−K (cosx)·(−sinx) 2 = ln(x +3)·(2x)+ln(cosx+3)sinx. 2 2 x ✭✷✮ ❯s✐♥❣ t❤❡ ❋✉♥❞❛♠❡♥t❛❧ ❚❤❡♦r❡♠ ♦❢ ❈❛❧❝✉❧✉s✱ ❣✐✈❡ ❛♥ ❛♥t✐❞❡r✐✈❛t✐✈❡ F(x) ♦❢ f(x) = sin (x) + e s❛t✐s❢②✐♥❣ F(3) = 0. ❨♦✉r ❛♥s✇❡r ❝❛♥ ✐♥✈♦❧✈❡ ❛ ❞❡✜♥✐t❡ ✐♥t❡❣r❛❧✳ ❙♦❧✉t✐♦♥✿ ❆❝❝♦r❞✐♥❣ t♦ t❤❡ ❋✉♥❞❛♠❡♥t❛❧ ❚❤❡♦r❡♠ ♦❢ ❈❛❧❝✉❧✉s✱ d Z x 2 2 2 t 2 x dx sin (t) + e dt = sin (x) +e . a ❚❤✉s✱ ❛♥② ❢✉♥❝t✐♦♥ ♦❢ t❤❡ ❢♦r♠ Z x 2 t2 F(x) = sin (t) + e dt a 2 2 ✐s ❛♥ ❛♥t✐❞❡r✐✈❛t✐✈❡ ♦❢ sin (x) + ex ✳ ❍♦✇❡✈❡r✱ ✇❡ ❛❧s♦ ♥❡❡❞ ♦✉r ❛♥t✐❞❡r✐✈❛t✐✈❡ t♦ s❛t✐s❢② F(3) = 0✳ P❧✉❣❣✐♥❣ t❤❛t ✐♥✱ ✇❡ ✜♥❞ t❤❛t Z 3 2 2 t 0 = sin (t) + e dt. a R ❖♥❡ ❡❛s② ✇❛② t♦ ❛❝❝♦♠♣❧✐s❤ t❤❛t ✐s ❜② s❡tt✐♥❣ a = 3✱ s✐♥❝❡ 3 f(t)dt = 0✳ ❚❤✉s✱ ♦✉r ❛♥t✐❞❡r✐✈❛t✐✈❡ ✐s 3 Z x 2 t2 Z x F(x) = sin (t) + e dt = f(t)dt . 3 3 Z x 2 ✭✸✮ ▲❡t F(x) = 0 (t −6t+8)dt. ✭❛✮ ❋✐♥❞ t❤❡ ❝r✐t✐❝❛❧ ♣♦✐♥ts ♦❢ F ✭✐✳❡✳ t❤❡ ♣♦✐♥ts ✇❤❡r❡ F′(x) = 0) ❛♥❞ ❞❡t❡r♠✐♥❡ ✇❤❡t❤❡r t❤❡② ❛r❡ ❧♦❝❛❧ ♠✐♥✐♠❛ ♦r ❧♦❝❛❧ ♠❛①✐♠❛✳ ❙♦❧✉t✐♦♥✿ ❲❡ ❝♦✉❧❞ t❛❦❡ ❛♥ ❛♥t✐❞❡r✐✈❛t✐✈❡ t♦ ❝♦♠♣✉t❡ F(x)✱ ❜✉t t❤❛t ✇♦✉❧❞ ❜❡ s✐❧❧② s✐♥❝❡ t❤❡ ♥❡①t st❡♣ ✐s t♦ t❛❦❡ ❛ ❞❡r✐✈❛t✐✈❡✳ ❚❤❡ ❋✉♥❞❛♠❡♥t❛❧ ❚❤❡♦r❡♠ ♦❢ ❈❛❧❝✉❧✉s t❡❧❧s ✉s t❤❛t ′ d Z x 2 2 F (x) = dx 0 (t −6t+8)dt = x −6x+8=(x−2)(x−4). ❚❤✉s✱ t❤❡ ❝r✐t✐❝❛❧ ♣♦✐♥ts ♦❢ F(x) ♦❝❝✉r ✇❤❡♥ 0 = (x−2)(x−4), t❤❛t ✐s✱ ✇❤❡♥ x = 2 ♦r x = 4✳ ■♥✈❡st✐❣❛t✐♥❣ t❤❡ ❡①♣r❡ss✐♦♥ F′(x) = (x−2)(x−4) ❢✉rt❤❡r✱ ✇❡ s❡❡ t❤❛t F′(x) > 0 ✇❤❡♥ x < 2 ♦r x > 4✱ ❛♥❞ F′(x) < 0 ✇❤❡♥ 2 < x < 4✳ ❚❤❡r❡❢♦r❡✱ t❤❡ ❢✉♥❝t✐♦♥ F(x) ✐s ✐♥❝r❡❛s✐♥❣ ✉♥t✐❧ ✇❡ ❣❡t t♦ x = 2✱ ❛t ✇❤✐❝❤♣♦✐♥t✐tst❛rts ❞❡❝r❡❛s✐♥❣✱ s♦ F(x) ❤❛s ❛ ❧♦❝❛❧ ♠❛①✐♠✉♠ ❛t x = 2✳ ❆❢t❡r t❤❛t✱ t❤❡ ❢✉♥❝t✐♦♥ ✐s ❞❡❝r❡❛s✐♥❣ ✉♥t✐❧ x = 4✱ ❛t ✇❤✐❝❤ ♣♦✐♥t ✐t st❛rts ✐♥❝r❡❛s✐♥❣✱ s♦ F(x) ❤❛s ❛ ❧♦❝❛❧ ♠✐♥✐♠✉♠ ❛t x = 4✳ ✭❜✮ ❋✐♥❞ t❤❡ ♣♦✐♥ts ♦❢ ✐♥✢❡❝t✐♦♥ ♦❢ F ✭✐✳❡✳ t❤❡ ♣♦✐♥ts ✇❤❡r❡ F′′(x) = 0✮ ❛♥❞ ❞❡t❡r♠✐♥❡ ✇❤❡t❤❡r t❤❡ ❝♦♥❝❛✈✐t② ❝❤❛♥❣❡s ❢r♦♠ ✉♣ t♦ ❞♦✇♥ ♦r ❢r♦♠ ❞♦✇♥ t♦ ✉♣ ❛t ❡❛❝❤ ♦♥❡✳ ❙♦❧✉t✐♦♥✿ ❲❡ ❛❧r❡❛❞② ❝♦♠♣✉t❡❞ F′(x)✱ s♦✱ ✉s✐♥❣ t❤❡ ♣r♦❞✉❝t r✉❧❡✱ ✇❡ ❝♦♠♣✉t❡ t❤❛t F′′(x) = d ((x−2)(x−4)) = 1·(x−4)+(x−2)·1=2x−6. dx ❙♦❧✈✐♥❣✱ ✇❡ ✜♥❞ t❤❛t F′′(x) = 0 ✇❤❡♥ x = 3✳ ▲♦♦❦✐♥❣ ❛t t❤❡ ❡①♣r❡ss✐♦♥ 2x − 6✱ ✇❤❡♥ x < 3✱ ✇❡ s❡❡ t❤❛t F′′(x) < 0✱ s♦ F ✐s ❝♦♥❝❛✈❡ ❞♦✇♥✳ ❲❤❡♥ x > 3✱ ✇❡ s❡❡ t❤❛t F′′(x) > 0✱ s♦ F ✐s ❝♦♥❝❛✈❡ ✉♣✳ ❚❤✉s✱ ❛t t❤❡ ✐♥✢❡❝t✐♦♥ ♣♦✐♥t ❛t x = 3✱ F ❝❤❛♥❣❡s ❢r♦♠ ❜❡✐♥❣ ❝♦♥❝❛✈❡ ❞♦✇♥ t♦ ❜❡✐♥❣ ❝♦♥❝❛✈❡ ✉♣✳
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