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Question Number 207493 Answers: 2 Comments: 0

lim_(n→∞) (((n − 1)/(n + 2)))^(n+3) = ?

$$\underset{\boldsymbol{\mathrm{n}}\rightarrow\infty} {\mathrm{lim}}\:\left(\frac{\mathrm{n}\:−\:\mathrm{1}}{\mathrm{n}\:+\:\mathrm{2}}\right)^{\boldsymbol{\mathrm{n}}+\mathrm{3}} \:=\:\:? \\ $$

Question Number 207482 Answers: 1 Comments: 0

Question Number 207477 Answers: 0 Comments: 8

is there any generale form for this sequense { ((u_(n+1) =((au_n +b)/(cu_n +d)))),((u_m =k)) :} I need u_n in terms of n i have try to derrive it for a long time but i cant

$${is}\:{there}\:{any}\:{generale}\:{form}\:{for}\:{this}\:{sequense}\: \\ $$$$\begin{cases}{{u}_{{n}+\mathrm{1}} =\frac{{au}_{{n}} +{b}}{{cu}_{{n}} +{d}}}\\{{u}_{{m}} ={k}}\end{cases} \\ $$$${I}\:{need}\:{u}_{{n}} \:{in}\:{terms}\:{of}\:{n}\:{i}\:{have}\:{try}\:{to}\:{derrive}\:{it}\:{for}\:{a}\:{long}\:{time}\:{but}\:{i}\:{cant} \\ $$

Question Number 207724 Answers: 1 Comments: 0

2 tg^3 x − 2 tg^2 x + 6 tg x = 3 , [0 ; 2𝛑] Sum of roots = ?

$$\mathrm{2}\:\mathrm{tg}^{\mathrm{3}} \:\boldsymbol{\mathrm{x}}\:−\:\mathrm{2}\:\mathrm{tg}^{\mathrm{2}} \:\boldsymbol{\mathrm{x}}\:+\:\mathrm{6}\:\mathrm{tg}\:\boldsymbol{\mathrm{x}}\:=\:\mathrm{3}\:\:\:,\:\:\:\left[\mathrm{0}\:;\:\mathrm{2}\boldsymbol{\pi}\right] \\ $$$$\mathrm{Sum}\:\mathrm{of}\:\mathrm{roots}\:=\:? \\ $$

Question Number 207723 Answers: 0 Comments: 2

lim∫_0 ^∞ (1−e^(−ncos(x)) )dx

$$\mathrm{li}{m}\int_{\mathrm{0}} ^{\infty} \left(\mathrm{1}−{e}^{−{ncos}\left({x}\right)} \right){dx} \\ $$

Question Number 207466 Answers: 2 Comments: 0

Question Number 207463 Answers: 1 Comments: 0

1 − sin^2 x = (√2) find: x = ?

$$\mathrm{1}\:−\:\mathrm{sin}^{\mathrm{2}} \:\mathrm{x}\:=\:\sqrt{\mathrm{2}}\:\:\:\:\:\mathrm{find}:\:\:\boldsymbol{\mathrm{x}}\:=\:? \\ $$

Question Number 207462 Answers: 0 Comments: 1

4 sin (x/2) = 1 find: x = ?

$$\mathrm{4}\:\mathrm{sin}\:\frac{\boldsymbol{\mathrm{x}}}{\mathrm{2}}\:=\:\mathrm{1}\:\:\:\:\:\mathrm{find}:\:\:\boldsymbol{\mathrm{x}}\:=\:? \\ $$

Question Number 207461 Answers: 0 Comments: 2

Question Number 207458 Answers: 0 Comments: 2

Question Number 207487 Answers: 1 Comments: 0

∣x^2 − 3x − 4∣ = ∣x − 4∣ find: min and max = ?

$$\mid\mathrm{x}^{\mathrm{2}} \:−\:\mathrm{3x}\:−\:\mathrm{4}\mid\:=\:\mid\mathrm{x}\:−\:\mathrm{4}\mid \\ $$$$\mathrm{find}:\:\:\:\boldsymbol{\mathrm{min}}\:\:\mathrm{and}\:\:\boldsymbol{\mathrm{max}}\:\:=\:\:? \\ $$

Question Number 207486 Answers: 2 Comments: 2

Question Number 207456 Answers: 0 Comments: 0

Question Number 207455 Answers: 0 Comments: 0

Question Number 207450 Answers: 1 Comments: 0

Find the relation between m and n for which the following holds ((d(y))/(d(x)))∣_(x=n) =(((d(x))/(d(y)))∣_(y=m) )^(−1)

$$\mathrm{Find}\:\mathrm{the}\:\mathrm{relation}\:\mathrm{between}\:{m}\:\mathrm{and}\:{n}\:\mathrm{for}\:\mathrm{which}\:\mathrm{the}\:\mathrm{following}\:\:\mathrm{holds} \\ $$$$\:\frac{{d}\left({y}\right)}{{d}\left({x}\right)}\mid_{{x}={n}} =\left(\frac{{d}\left({x}\right)}{{d}\left({y}\right)}\mid_{{y}={m}} \right)^{−\mathrm{1}} \\ $$

Question Number 207451 Answers: 0 Comments: 0

find the volume in the first quadrant of the solid obtained by rotating the region bounded by the curves x = sinh(y) , x = cosh(y) about y axis (use washer method) ?

$${find}\:{the}\:{volume}\:{in}\:{the}\:{first}\:{quadrant} \\ $$$$\:{of}\:{the}\:{solid}\:{obtained}\:{by}\:{rotating} \\ $$$${the}\:{region}\:{bounded}\:{by}\:{the}\:{curves}\: \\ $$$${x}\:=\:{sinh}\left({y}\right)\:,\:{x}\:=\:{cosh}\left({y}\right)\:{about}\:{y}\:{axis}\:\left({use}\:{washer}\:{method}\right)\:? \\ $$

Question Number 207442 Answers: 1 Comments: 3

If y=f(x), (d^2 x/dy^2 )=e^(y+1) , and the tangent line to the curve of the function f(x) on the point (x_1 ,−1) is paralel to the straight line g(x)=x−3, then find f′(x).

$$\mathrm{If}\:{y}={f}\left({x}\right),\:\frac{{d}^{\mathrm{2}} {x}}{{dy}^{\mathrm{2}} }={e}^{{y}+\mathrm{1}} ,\:\mathrm{and}\:\mathrm{the}\:\mathrm{tangent}\:\mathrm{line}\:\mathrm{to}\:\mathrm{the}\:\mathrm{curve}\:\mathrm{of}\:\mathrm{the}\:\mathrm{function}\:{f}\left({x}\right)\:\mathrm{on}\:\mathrm{the}\:\mathrm{point} \\ $$$$\left({x}_{\mathrm{1}} ,−\mathrm{1}\right)\:\mathrm{is}\:\mathrm{paralel}\:\mathrm{to}\:\mathrm{the}\:\mathrm{straight}\:\mathrm{line}\:{g}\left({x}\right)={x}−\mathrm{3},\:\mathrm{then}\:\mathrm{find}\:{f}'\left({x}\right). \\ $$

Question Number 207436 Answers: 1 Comments: 2

a, b∈N_+ , ((b+1)/a)+((a+1)/b)∈Z. Prove that (a, b)≤(√(a+b.))

$${a},\:{b}\in\mathbb{N}_{+} ,\:\frac{{b}+\mathrm{1}}{{a}}+\frac{{a}+\mathrm{1}}{{b}}\in\mathbb{Z}.\:\mathrm{Prove}\:\mathrm{that}\: \\ $$$$\left({a},\:{b}\right)\leqslant\sqrt{{a}+{b}.} \\ $$

Question Number 207434 Answers: 0 Comments: 0

Relating to question 207407 x^3 −12x^2 +27x−17=0 Let x=t+4 t^3 −21t−37=0 The Trigonometric Solution gives these: x_1 =4−2(√7)cos ((π+2sin^(−1) ((37(√7))/(98)))/6) x_2 =4−2(√7)sin ((sin^(−1) ((37(√7))/(98)))/3) x_3 =4+2(√7)sin ((π+sin^(−1) ((37(√7))/(98)))/3) Prove these identities: x_1 =2−((1+2sin (π/(18)))/(2cos (π/9))) x_2 =2+((1+2cos (π/9))/(2cos ((2π)/9))) x_3 =((1+2(√3)sin ((2π)/9))/(2sin (π/(18))))

$$\mathrm{Relating}\:\mathrm{to}\:\mathrm{question}\:\mathrm{207407} \\ $$$${x}^{\mathrm{3}} −\mathrm{12}{x}^{\mathrm{2}} +\mathrm{27}{x}−\mathrm{17}=\mathrm{0} \\ $$$$\mathrm{Let}\:{x}={t}+\mathrm{4} \\ $$$${t}^{\mathrm{3}} −\mathrm{21}{t}−\mathrm{37}=\mathrm{0} \\ $$$$\mathrm{The}\:\mathrm{Trigonometric}\:\mathrm{Solution}\:\mathrm{gives}\:\mathrm{these}: \\ $$$${x}_{\mathrm{1}} =\mathrm{4}−\mathrm{2}\sqrt{\mathrm{7}}\mathrm{cos}\:\frac{\pi+\mathrm{2sin}^{−\mathrm{1}} \:\frac{\mathrm{37}\sqrt{\mathrm{7}}}{\mathrm{98}}}{\mathrm{6}} \\ $$$${x}_{\mathrm{2}} =\mathrm{4}−\mathrm{2}\sqrt{\mathrm{7}}\mathrm{sin}\:\frac{\mathrm{sin}^{−\mathrm{1}} \:\frac{\mathrm{37}\sqrt{\mathrm{7}}}{\mathrm{98}}}{\mathrm{3}} \\ $$$${x}_{\mathrm{3}} =\mathrm{4}+\mathrm{2}\sqrt{\mathrm{7}}\mathrm{sin}\:\frac{\pi+\mathrm{sin}^{−\mathrm{1}} \:\frac{\mathrm{37}\sqrt{\mathrm{7}}}{\mathrm{98}}}{\mathrm{3}} \\ $$$$\mathrm{Prove}\:\mathrm{these}\:\mathrm{identities}: \\ $$$${x}_{\mathrm{1}} =\mathrm{2}−\frac{\mathrm{1}+\mathrm{2sin}\:\frac{\pi}{\mathrm{18}}}{\mathrm{2cos}\:\:\frac{\pi}{\mathrm{9}}} \\ $$$${x}_{\mathrm{2}} =\mathrm{2}+\frac{\mathrm{1}+\mathrm{2cos}\:\frac{\pi}{\mathrm{9}}}{\mathrm{2cos}\:\frac{\mathrm{2}\pi}{\mathrm{9}}} \\ $$$${x}_{\mathrm{3}} =\frac{\mathrm{1}+\mathrm{2}\sqrt{\mathrm{3}}\mathrm{sin}\:\frac{\mathrm{2}\pi}{\mathrm{9}}}{\mathrm{2sin}\:\frac{\pi}{\mathrm{18}}} \\ $$

Question Number 207435 Answers: 1 Comments: 0

y=e^t −e^(−t) and x = e^t +e^(−t) does this parametric equation resembles circle or ellipse or hyperbola or parabola and why?

$${y}={e}^{{t}} −{e}^{−{t}} \:{and}\:{x}\:=\:{e}^{{t}} +{e}^{−{t}} \:{does}\:{this}\:{parametric}\:{equation}\:{resembles} \\ $$$$\:{circle}\:{or}\:{ellipse}\:{or}\:{hyperbola}\:{or}\:{parabola}\:{and}\:{why}? \\ $$

Question Number 207426 Answers: 1 Comments: 0

Question Number 207424 Answers: 0 Comments: 0

f_n (x):=∫e^((2x)/3) ((cos(x))/( (cos(x)+sin(x))^(n/3) ))dx=...? for n=1, i found f_1 (x)=(3/4)e^((2x)/3) (cos(x)+sin(x))^(2/3) + C is there any ideas for a general case or the case n=2?

$${f}_{{n}} \left({x}\right):=\int{e}^{\frac{\mathrm{2}{x}}{\mathrm{3}}} \frac{{cos}\left({x}\right)}{\:\left({cos}\left({x}\right)+{sin}\left({x}\right)\right)^{\frac{{n}}{\mathrm{3}}} }{dx}=...? \\ $$$${for}\:{n}=\mathrm{1},\:{i}\:{found}\: \\ $$$$\:\:\:\:\:\:{f}_{\mathrm{1}} \left({x}\right)=\frac{\mathrm{3}}{\mathrm{4}}{e}^{\frac{\mathrm{2}{x}}{\mathrm{3}}} \left({cos}\left({x}\right)+{sin}\left({x}\right)\right)^{\frac{\mathrm{2}}{\mathrm{3}}} +\:{C} \\ $$$${is}\:{there}\:{any}\:{ideas}\:{for}\:{a}\:{general}\:{case}\:{or} \\ $$$${the}\:{case}\:{n}=\mathrm{2}? \\ $$

Question Number 207423 Answers: 2 Comments: 0

⇃

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Question Number 207416 Answers: 2 Comments: 0

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Question Number 207395 Answers: 1 Comments: 0

Geometric series: ((b_4 ∙ b_7 ∙ b_(10) )/(b_1 ∙ b_3 ∙ b_5 )) = 2^(12) find: (b_5 /b_2 ) = ?

$$\mathrm{Geometric}\:\mathrm{series}: \\ $$$$\frac{\mathrm{b}_{\mathrm{4}} \:\centerdot\:\mathrm{b}_{\mathrm{7}} \:\centerdot\:\mathrm{b}_{\mathrm{10}} }{\mathrm{b}_{\mathrm{1}} \:\centerdot\:\mathrm{b}_{\mathrm{3}} \:\centerdot\:\mathrm{b}_{\mathrm{5}} }\:\:=\:\:\mathrm{2}^{\mathrm{12}} \:\:\:\:\:\mathrm{find}:\:\:\:\frac{\mathrm{b}_{\mathrm{5}} }{\mathrm{b}_{\mathrm{2}} }\:\:=\:\:? \\ $$

Question Number 207394 Answers: 1 Comments: 0

(a/b) = (c/d) a^3 − b^3 = 625 c^3 − d^3 = 1 Find: a,b,c,d = ?

$$\frac{\mathrm{a}}{\mathrm{b}}\:\:=\:\:\frac{\mathrm{c}}{\mathrm{d}} \\ $$$$\mathrm{a}^{\mathrm{3}} \:−\:\mathrm{b}^{\mathrm{3}} \:=\:\mathrm{625} \\ $$$$\mathrm{c}^{\mathrm{3}} \:−\:\mathrm{d}^{\mathrm{3}} \:=\:\mathrm{1} \\ $$$$\mathrm{Find}:\:\:\:\mathrm{a},\mathrm{b},\mathrm{c},\mathrm{d}\:=\:? \\ $$

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