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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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