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Question Number 197343 Answers: 0 Comments: 0

calculate ∫_0 ^(π/2) ln(cosx).ln(sinx)dx

$${calculate}\:\int_{\mathrm{0}} ^{\frac{\pi}{\mathrm{2}}} {ln}\left({cosx}\right).{ln}\left({sinx}\right){dx} \\ $$

Question Number 197338 Answers: 1 Comments: 0

∫(x^2 /(x^2 +1))dx

$$\int\frac{{x}^{\mathrm{2}} }{{x}^{\mathrm{2}} +\mathrm{1}}{dx} \\ $$

Question Number 197336 Answers: 2 Comments: 0

lim_(x→+∞) ((1/x^2 )+cosx)=?

$${lim}_{{x}\rightarrow+\infty} \left(\frac{\mathrm{1}}{{x}^{\mathrm{2}} }+\mathrm{cos}{x}\right)=? \\ $$

Question Number 197327 Answers: 2 Comments: 0

trigonometry... P = Π_(k=1) ^(44) ( 1 + tan(k) ) = ?

$$ \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:{trigonometry}... \\ $$$$ \\ $$$$\:\:\:\:\:\:\:\:\:\:\mathrm{P}\:=\:\underset{{k}=\mathrm{1}} {\overset{\mathrm{44}} {\prod}}\left(\:\:\mathrm{1}\:+\:{tan}\left({k}\right)\:\right)\:=\:?\:\: \\ $$$$ \\ $$$$\:\:\:\:\:\:\:\: \\ $$

Question Number 197335 Answers: 1 Comments: 0

Question Number 197325 Answers: 1 Comments: 0

Question Number 197323 Answers: 1 Comments: 0

If f(x)=((sin(x))/x) and S_n (α)=Σ_(k=1) ^n [f(kπ+(π/α))+f(kπ−(π/α))] (α>1) Prove that lim_(n→+∞) S_n (α)=1−f((π/α))

$$\mathrm{If}\:\mathrm{f}\left(\mathrm{x}\right)=\frac{\mathrm{sin}\left(\mathrm{x}\right)}{\mathrm{x}}\:\:\:\mathrm{and}\:\mathrm{S}_{\mathrm{n}} \left(\alpha\right)=\underset{\mathrm{k}=\mathrm{1}} {\overset{\mathrm{n}} {\sum}}\left[\mathrm{f}\left(\mathrm{k}\pi+\frac{\pi}{\alpha}\right)+\mathrm{f}\left(\mathrm{k}\pi−\frac{\pi}{\alpha}\right)\right]\:\:\:\:\left(\alpha>\mathrm{1}\right) \\ $$$$\mathrm{Prove}\:\mathrm{that}\:\underset{\mathrm{n}\rightarrow+\infty} {\:\mathrm{lim}}\:\mathrm{S}_{\mathrm{n}} \left(\alpha\right)=\mathrm{1}−\mathrm{f}\left(\frac{\pi}{\alpha}\right) \\ $$

Question Number 197320 Answers: 1 Comments: 0

Σ_(k=1) ^n (−1)^(k(k+1))

$$\underset{{k}=\mathrm{1}} {\overset{{n}} {\sum}}\left(−\mathrm{1}\right)^{{k}\left({k}+\mathrm{1}\right)} \\ $$

Question Number 197317 Answers: 0 Comments: 0

if x = ((cos θ)/u) , y = ((sin θ)/u) and z = f(x,y) then show that (∂^2 z/∂x^2 ) + (∂^2 z/∂y^2 ) = u^4 (∂^2 z/∂u^2 ) + u^3 (∂z/∂u) + u^4 (∂^2 z/∂θ^2 )

$$\:\mathrm{if}\:\:\:\mathrm{x}\:\:=\:\:\frac{\mathrm{cos}\:\theta}{\mathrm{u}}\:\:,\:\mathrm{y}\:\:=\:\frac{\mathrm{sin}\:\theta}{\mathrm{u}}\:\:{and}\:\mathrm{z}\:\:=\:\:\mathrm{f}\left(\mathrm{x},\mathrm{y}\right) \\ $$$$\mathrm{then}\:\mathrm{show}\:\mathrm{that}\: \\ $$$$\:\:\:\frac{\partial^{\mathrm{2}} \mathrm{z}}{\partial\mathrm{x}^{\mathrm{2}} }\:+\:\frac{\partial^{\mathrm{2}} \mathrm{z}}{\partial\mathrm{y}^{\mathrm{2}} }\:=\:\mathrm{u}^{\mathrm{4}} \:\frac{\partial^{\mathrm{2}} \mathrm{z}}{\partial\mathrm{u}^{\mathrm{2}} }\:+\:\mathrm{u}^{\mathrm{3}} \:\frac{\partial\mathrm{z}}{\partial\mathrm{u}}\:+\:\mathrm{u}^{\mathrm{4}} \:\frac{\partial^{\mathrm{2}} \mathrm{z}}{\partial\theta^{\mathrm{2}} } \\ $$

Question Number 197312 Answers: 1 Comments: 0

(((log_2 20)^2 −(log_2 5)^2 )/(log_2 10))=?

$$\frac{\left({log}_{\mathrm{2}} \mathrm{20}\right)^{\mathrm{2}} −\left({log}_{\mathrm{2}} \mathrm{5}\right)^{\mathrm{2}} }{{log}_{\mathrm{2}} \mathrm{10}}=? \\ $$

Question Number 197311 Answers: 1 Comments: 0

Prove that _(n+1) C_r = _n C_r + _n C_(r−1)

$$\:\:\:\:\:\mathrm{Prove}\:\mathrm{that}\: \\ $$$$\:\:\:\:\:\:_{\mathrm{n}+\mathrm{1}} \:\mathrm{C}_{\mathrm{r}} \:=\:_{\mathrm{n}} \mathrm{C}_{\mathrm{r}} \:+\:_{\mathrm{n}} \mathrm{C}_{\mathrm{r}−\mathrm{1}} \: \\ $$

Question Number 197310 Answers: 1 Comments: 0

Question Number 197301 Answers: 1 Comments: 0

how do i calculate this lim_(x→-∞) ((x^4 +2x^2 +x−2)/(x^3 +2x^2 +x−1)) multiplying both numerator and denumerator by (1/x^4 ) lim_(x→-∞) ((1+(2/x^2 )+(1/x^3 )−(2/x^4 ))/((1/x)+(2/x^2 )+(1/x^3 )−(1/x^4 ))) ((1+0+0−0)/(0+0+0−0)) ∞ which is not true the answer is -∞, i tried multiplying (1/x^3 ) and got -∞ but still confused what did i do wrong using (1/x^4 )

$$ \\ $$$$\:{how}\:{do}\:{i}\:{calculate}\:{this} \\ $$$$\:\underset{{x}\rightarrow-\infty} {\mathrm{lim}}\:\frac{{x}^{\mathrm{4}} +\mathrm{2}{x}^{\mathrm{2}} +{x}−\mathrm{2}}{{x}^{\mathrm{3}} +\mathrm{2}{x}^{\mathrm{2}} +{x}−\mathrm{1}} \\ $$$$\:{multiplying}\:{both}\:{numerator} \\ $$$$\:{and}\:{denumerator}\:{by}\:\frac{\mathrm{1}}{{x}^{\mathrm{4}} } \\ $$$$\:\underset{{x}\rightarrow-\infty} {\mathrm{lim}}\:\frac{\mathrm{1}+\frac{\mathrm{2}}{{x}^{\mathrm{2}} }+\frac{\mathrm{1}}{{x}^{\mathrm{3}} }−\frac{\mathrm{2}}{{x}^{\mathrm{4}} }}{\frac{\mathrm{1}}{{x}}+\frac{\mathrm{2}}{{x}^{\mathrm{2}} }+\frac{\mathrm{1}}{{x}^{\mathrm{3}} }−\frac{\mathrm{1}}{{x}^{\mathrm{4}} }} \\ $$$$\:\frac{\mathrm{1}+\mathrm{0}+\mathrm{0}−\mathrm{0}}{\mathrm{0}+\mathrm{0}+\mathrm{0}−\mathrm{0}} \\ $$$$\:\infty \\ $$$$\:{which}\:{is}\:{not}\:{true}\:{the}\:{answer}\:{is}\:-\infty, \\ $$$$\:{i}\:{tried}\:{multiplying}\:\frac{\mathrm{1}}{{x}^{\mathrm{3}} }\:{and}\:{got}\:-\infty \\ $$$$\:{but}\:{still}\:{confused}\:{what}\:{did}\:{i}\:{do}\:{wrong} \\ $$$$\:{using}\:\frac{\mathrm{1}}{{x}^{\mathrm{4}} } \\ $$$$ \\ $$

Question Number 197299 Answers: 1 Comments: 0

((−64))^(1/6) −((−10))^(1/(10)) =? I need so much plz

$$\sqrt[{\mathrm{6}}]{−\mathrm{64}}−\sqrt[{\mathrm{10}}]{−\mathrm{10}}=? \\ $$$$\boldsymbol{{I}}\:\boldsymbol{\mathrm{need}}\:\boldsymbol{\mathrm{so}}\:\boldsymbol{\mathrm{much}}\:\boldsymbol{\mathrm{plz}} \\ $$

Question Number 197292 Answers: 2 Comments: 0

lim_(n→∞) ∫_(0 ) ^1 ((nx^(n−1) )/(1+x))dx = ?

$$\:\:\:\underset{{n}\rightarrow\infty} {\mathrm{lim}}\:\int_{\mathrm{0}\:} ^{\mathrm{1}} \frac{{nx}^{{n}−\mathrm{1}} }{\mathrm{1}+{x}}{dx}\:\:=\:\:\:? \\ $$

Question Number 197290 Answers: 0 Comments: 1

Question Number 197287 Answers: 0 Comments: 3

answer to the question number 197017 AF=FI & AG=GJ⇒FG=(1/2)IJ=(1/6)BC △FGH is squilatral ⇒ △FGH≈△ABC ⇒(S_(FGH) /S_(SBC) ) =(1/(36 )) ✓

$${answer}\:{to}\:{the}\:{question}\:{number} \\ $$$$\mathrm{197017} \\ $$$${AF}={FI}\:\&\:\:{AG}={GJ}\Rightarrow{FG}=\frac{\mathrm{1}}{\mathrm{2}}{IJ}=\frac{\mathrm{1}}{\mathrm{6}}{BC} \\ $$$$\bigtriangleup{FGH}\:\:{is}\:\:{squilatral}\:\Rightarrow\:\bigtriangleup{FGH}\approx\bigtriangleup{ABC} \\ $$$$\Rightarrow\frac{{S}_{{FGH}} }{{S}_{{SBC}} }\:=\frac{\mathrm{1}}{\mathrm{36}\:}\:\checkmark \\ $$$$ \\ $$

Question Number 197282 Answers: 1 Comments: 0

lim_(x→0) ((sin^2 x−sin x^2 )/(x^2 (cos^2 x−cos x^2 ))) =?

$$\:\:\:\:\:\:\underset{{x}\rightarrow\mathrm{0}} {\mathrm{lim}}\:\frac{\mathrm{sin}\:^{\mathrm{2}} \mathrm{x}−\mathrm{sin}\:\mathrm{x}^{\mathrm{2}} }{\mathrm{x}^{\mathrm{2}} \:\left(\mathrm{cos}\:^{\mathrm{2}} \mathrm{x}−\mathrm{cos}\:\mathrm{x}^{\mathrm{2}} \:\right)}\:=? \\ $$

Question Number 197281 Answers: 2 Comments: 0

lim_(x→0) ((sin x−x+2x^5 )/(3x^3 )) =?

$$\:\:\:\:\:\:\underset{{x}\rightarrow\mathrm{0}} {\mathrm{lim}}\:\frac{\mathrm{sin}\:\mathrm{x}−\mathrm{x}+\mathrm{2x}^{\mathrm{5}} }{\mathrm{3x}^{\mathrm{3}} }\:=? \\ $$

Question Number 197277 Answers: 1 Comments: 0

Question Number 197275 Answers: 1 Comments: 0

how do i prove this, help please. ∣((x^2 −2x−3)/(x^2 +2x+4))∣≤(5/4),∣x∣≤2

$$ \\ $$$$\:{how}\:{do}\:{i}\:{prove}\:{this},\:{help}\:{please}. \\ $$$$\:\mid\frac{{x}^{\mathrm{2}} −\mathrm{2}{x}−\mathrm{3}}{{x}^{\mathrm{2}} +\mathrm{2}{x}+\mathrm{4}}\mid\leqslant\frac{\mathrm{5}}{\mathrm{4}},\mid{x}\mid\leqslant\mathrm{2} \\ $$$$ \\ $$$$ \\ $$

Question Number 197274 Answers: 0 Comments: 1

Question Number 197272 Answers: 2 Comments: 0

How to calculate this integral ∫^( (π/2)) _( 0) ((ln(1+sint))/(sint))dt

$$\mathrm{How}\:\mathrm{to}\:\mathrm{calculate}\:\mathrm{this}\:\mathrm{integral} \\ $$$$\underset{\:\mathrm{0}} {\int}^{\:\frac{\pi}{\mathrm{2}}} \:\frac{\mathrm{ln}\left(\mathrm{1}+{sint}\right)}{{sint}}{dt} \\ $$

Question Number 198332 Answers: 0 Comments: 1

Of men that attended a party, 30 of them wore coats, 20 wore ties and 10 wore hats. There were 4 men who wore coats and tie, or tie and hat or coat and hat. 14 men wore tie only with no coat and hat. Find the number of men who wore: a) coat, tie and hat b) hat only with no coat and hat.

$${Of}\:{men}\:{that}\:{attended}\:{a}\:{party},\:\mathrm{30}\:{of} \\ $$$${them}\:{wore}\:{coats},\:\mathrm{20}\:{wore}\:{ties}\:{and}\:\mathrm{10} \\ $$$${wore}\:{hats}.\:{There}\:{were}\:\mathrm{4}\:{men}\:{who}\:{wore} \\ $$$${coats}\:{and}\:{tie},\:{or}\:{tie}\:{and}\:{hat}\:{or}\:{coat}\:{and} \\ $$$${hat}.\:\mathrm{14}\:{men}\:{wore}\:{tie}\:{only}\:{with}\:{no} \\ $$$${coat}\:{and}\:{hat}.\:{Find}\:{the}\:{number}\:{of}\:{men} \\ $$$${who}\:{wore}: \\ $$$$\left.{a}\right)\:{coat},\:{tie}\:{and}\:{hat} \\ $$$$\left.{b}\right)\:{hat}\:{only}\:{with}\:{no}\:{coat}\:{and}\:{hat}. \\ $$

Question Number 198288 Answers: 1 Comments: 0

Question Number 197255 Answers: 0 Comments: 0

log 2=a log 3=b log 72=?

$$\mathrm{log}\:\mathrm{2}={a} \\ $$$$\mathrm{log}\:\mathrm{3}={b} \\ $$$$\mathrm{log}\:\mathrm{72}=? \\ $$

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