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Question Number 44712 Answers: 3 Comments: 0

Question Number 44708 Answers: 1 Comments: 0

Let A,B be two n×n matrices such that A+B=AB then prove : AB=BA ?

$${Let}\:{A},{B}\:{be}\:{two}\:{n}×{n}\:{matrices}\:{such} \\ $$$${that}\:{A}+{B}={AB}\:{then}\:{prove}\:: \\ $$$${AB}={BA}\:? \\ $$

Question Number 44702 Answers: 0 Comments: 0

Question Number 44697 Answers: 0 Comments: 0

prove that:− ∫_0 ^∞ (t^(a−1) /(1+t))dt = (𝛑/(sin(𝛑a)))

$$\boldsymbol{{prove}}\:\boldsymbol{{that}}:− \\ $$$$\int_{\mathrm{0}} ^{\infty} \frac{\boldsymbol{{t}}^{\boldsymbol{{a}}−\mathrm{1}} }{\mathrm{1}+\boldsymbol{{t}}}\boldsymbol{{dt}}\:=\:\frac{\boldsymbol{\pi}}{\boldsymbol{{sin}}\left(\boldsymbol{\pi{a}}\right)} \\ $$

Question Number 44704 Answers: 2 Comments: 0

Find the general solution of : 311x − 112y = 73

$$\mathrm{Find}\:\mathrm{the}\:\mathrm{general}\:\mathrm{solution}\:\mathrm{of}\::\:\:\:\:\:\:\:\:\:\:\:\mathrm{311x}\:−\:\mathrm{112y}\:=\:\mathrm{73} \\ $$

Question Number 44706 Answers: 0 Comments: 4

let f_α (x) = ((cos(αx))/(1+x^2 )) 1) calculate f^((n)) (x) and f^((n)) (0) 2) developp f at integr serie 3) give ∫_0 ^x f_α (t) dt at form of serie 4) developp ∫_0 ^∞ f_α (t)dt at integr serie .

$${let}\:{f}_{\alpha} \left({x}\right)\:=\:\frac{{cos}\left(\alpha{x}\right)}{\mathrm{1}+{x}^{\mathrm{2}} } \\ $$$$\left.\mathrm{1}\right)\:{calculate}\:{f}^{\left({n}\right)} \left({x}\right)\:{and}\:{f}^{\left({n}\right)} \left(\mathrm{0}\right) \\ $$$$\left.\mathrm{2}\right)\:{developp}\:{f}\:{at}\:{integr}\:{serie} \\ $$$$\left.\mathrm{3}\right)\:{give}\:\int_{\mathrm{0}} ^{{x}} \:{f}_{\alpha} \left({t}\right)\:{dt}\:\:{at}\:{form}\:{of}\:{serie}\: \\ $$$$\left.\mathrm{4}\right)\:{developp}\:\:\int_{\mathrm{0}} ^{\infty} \:\:\:\:{f}_{\alpha} \left({t}\right){dt}\:\:{at}\:\:{integr}\:{serie}\:. \\ $$

Question Number 44696 Answers: 1 Comments: 1

∫(1/(1+x^4 ))dx = ?

$$\int\frac{\mathrm{1}}{\mathrm{1}+\boldsymbol{\mathrm{x}}^{\mathrm{4}} }\boldsymbol{\mathrm{dx}}\:=\:? \\ $$

Question Number 44695 Answers: 0 Comments: 2

∫(e^(√(t−1)) /t)dt = ?

$$\int\frac{\boldsymbol{\mathrm{e}}^{\sqrt{\boldsymbol{\mathrm{t}}−\mathrm{1}}} }{\boldsymbol{\mathrm{t}}}\boldsymbol{\mathrm{dt}}\:=\:? \\ $$

Question Number 44691 Answers: 1 Comments: 1

Question Number 44676 Answers: 1 Comments: 6

Question Number 44652 Answers: 2 Comments: 4

Prove that lim_(x→0) (((1+ax)^(1/b) −1)/x) = (a/b).

$${Prove}\:{that}\:\underset{{x}\rightarrow\mathrm{0}} {\mathrm{lim}}\:\frac{\left(\mathrm{1}+{ax}\right)^{\frac{\mathrm{1}}{{b}}} −\mathrm{1}}{{x}}\:=\:\frac{{a}}{{b}}. \\ $$

Question Number 44639 Answers: 0 Comments: 1

∫(1/(1+(log x)^2 ))dx=?

$$\int\frac{\mathrm{1}}{\mathrm{1}+\left(\boldsymbol{\mathrm{log}}\:\boldsymbol{\mathrm{x}}\right)^{\mathrm{2}} }\boldsymbol{\mathrm{dx}}=? \\ $$$$ \\ $$

Question Number 44636 Answers: 1 Comments: 0

Question Number 44654 Answers: 1 Comments: 4

∫(e^x /(1+x^2 ))dx=?

$$\int\frac{\boldsymbol{\mathrm{e}}^{\boldsymbol{\mathrm{x}}} }{\mathrm{1}+\boldsymbol{\mathrm{x}}^{\mathrm{2}} }\boldsymbol{\mathrm{dx}}=? \\ $$

Question Number 44623 Answers: 1 Comments: 0

given that sin^(−1) x+sin^(−1) y=c show that (dy/dx)+(√((1−y^2 )/(1−x^2 )))=0

$$\boldsymbol{\mathrm{given}}\:\boldsymbol{\mathrm{that}}\:\boldsymbol{\mathrm{sin}}^{−\mathrm{1}} \boldsymbol{{x}}+\boldsymbol{\mathrm{sin}}^{−\mathrm{1}} \boldsymbol{{y}}=\boldsymbol{\mathrm{c}} \\ $$$$\boldsymbol{\mathrm{show}}\:\boldsymbol{\mathrm{that}}\:\frac{\boldsymbol{{dy}}}{\boldsymbol{{dx}}}+\sqrt{\frac{\mathrm{1}−\boldsymbol{{y}}^{\mathrm{2}} }{\mathrm{1}−\boldsymbol{{x}}^{\mathrm{2}} }}=\mathrm{0} \\ $$

Question Number 44622 Answers: 1 Comments: 0

if y=ln[tan((𝛑/4)+(x/2))] show that (dy/dx)=secx

$$\boldsymbol{\mathrm{if}}\:\boldsymbol{{y}}=\boldsymbol{\mathrm{ln}}\left[\boldsymbol{\mathrm{tan}}\left(\frac{\boldsymbol{\pi}}{\mathrm{4}}+\frac{\boldsymbol{{x}}}{\mathrm{2}}\right)\right]\:\boldsymbol{\mathrm{show}}\:\boldsymbol{\mathrm{that}} \\ $$$$\frac{\boldsymbol{{dy}}}{\boldsymbol{{dx}}}=\boldsymbol{\mathrm{sec}{x}} \\ $$

Question Number 44621 Answers: 2 Comments: 0

Question Number 44613 Answers: 0 Comments: 1

Question Number 44612 Answers: 2 Comments: 0

Prove that One factor of determinant (((a^2 +x),( ab),( ac)),(( ab),(b^2 +x),( cb)),(( ca),( cb),(c^2 +x))) is x^2 .

$${Prove}\:{that}\:\mathrm{One}\:\mathrm{factor}\:\mathrm{of}\begin{vmatrix}{{a}^{\mathrm{2}} +{x}}&{\:\:{ab}}&{\:\:{ac}}\\{\:\:{ab}}&{{b}^{\mathrm{2}} +{x}}&{\:\:{cb}}\\{\:\:{ca}}&{\:\:{cb}}&{{c}^{\mathrm{2}} +{x}}\end{vmatrix}\:\mathrm{is}\:{x}^{\mathrm{2}} . \\ $$

Question Number 44604 Answers: 1 Comments: 1

∫[((log x − 1)/(1+(log x)^2 ))]^2 dx = (x/((log x)^2 +1))+C

$$\int\left[\frac{\boldsymbol{\mathrm{log}}\:\boldsymbol{\mathrm{x}}\:\:−\:\:\mathrm{1}}{\mathrm{1}+\left(\boldsymbol{\mathrm{log}}\:\boldsymbol{\mathrm{x}}\right)^{\mathrm{2}} }\right]^{\mathrm{2}} \boldsymbol{\mathrm{dx}}\:\:=\:\:\frac{\boldsymbol{\mathrm{x}}}{\left(\boldsymbol{\mathrm{log}}\:\boldsymbol{\mathrm{x}}\right)^{\mathrm{2}} +\mathrm{1}}+\boldsymbol{\mathrm{C}} \\ $$

Question Number 44602 Answers: 0 Comments: 0

∫(e^x /(1+x^2 )) dx = ?

$$\int\frac{\boldsymbol{{e}}^{\boldsymbol{\mathrm{x}}} }{\mathrm{1}+\boldsymbol{\mathrm{x}}^{\mathrm{2}} }\:\boldsymbol{\mathrm{dx}}\:=\:\:? \\ $$

Question Number 44587 Answers: 1 Comments: 2

calculate ∫_0 ^∞ (dt/(1+t^(2018) ))

$${calculate}\:\int_{\mathrm{0}} ^{\infty} \:\:\:\frac{{dt}}{\mathrm{1}+{t}^{\mathrm{2018}} } \\ $$

Question Number 44584 Answers: 1 Comments: 5

Prove that if a, b, c ∈ Z and a^2 + b^2 = c^2 , then 3 ∣ ab

$$\mathrm{Prove}\:\mathrm{that}\:\mathrm{if}\:\:{a},\:{b},\:{c}\:\in\:\mathbb{Z}\:\:\mathrm{and}\:\:{a}^{\mathrm{2}} \:+\:{b}^{\mathrm{2}} \:=\:{c}^{\mathrm{2}} ,\:\mathrm{then} \\ $$$$\mathrm{3}\:\mid\:{ab} \\ $$

Question Number 44674 Answers: 0 Comments: 1

solving some integrals we might meet some of the following functions which cannot be solved with elementar knowledge but tables should exist somewhere in the depth of the www... these links might be interesting exponential integral ∫(e^(−x) /x)dx en.wikipedia.org/wiki/Exponential_integral logarithmic integral ∫(dx/(ln x)) en.wikipedia.org/wiki/Logarithmic_integral_function also see en.wikipedia.org/wiki/Polylogarithm trigonometric integrals i.e. ∫((sin x)/x)dx en.wikipedia.org/wiki/Trigonometric_integral

$$\mathrm{solving}\:\mathrm{some}\:\mathrm{integrals}\:\mathrm{we}\:\mathrm{might}\:\mathrm{meet}\:\mathrm{some} \\ $$$$\mathrm{of}\:\mathrm{the}\:\mathrm{following}\:\mathrm{functions}\:\mathrm{which}\:\mathrm{cannot}\:\mathrm{be} \\ $$$$\mathrm{solved}\:\mathrm{with}\:\mathrm{elementar}\:\mathrm{knowledge}\:\mathrm{but}\:\mathrm{tables} \\ $$$$\mathrm{should}\:\mathrm{exist}\:\mathrm{somewhere}\:\mathrm{in}\:\mathrm{the}\:\mathrm{depth}\:\mathrm{of}\:\mathrm{the} \\ $$$$\mathrm{www}... \\ $$$$\mathrm{these}\:\mathrm{links}\:\mathrm{might}\:\mathrm{be}\:\mathrm{interesting} \\ $$$$ \\ $$$$\mathrm{exponential}\:\mathrm{integral} \\ $$$$\int\frac{\mathrm{e}^{−{x}} }{{x}}{dx} \\ $$$$\mathrm{en}.\mathrm{wikipedia}.\mathrm{org}/\mathrm{wiki}/\mathrm{Exponential\_integral} \\ $$$$ \\ $$$$\mathrm{logarithmic}\:\mathrm{integral} \\ $$$$\int\frac{{dx}}{\mathrm{ln}\:{x}} \\ $$$$\mathrm{en}.\mathrm{wikipedia}.\mathrm{org}/\mathrm{wiki}/\mathrm{Logarithmic\_integral\_function} \\ $$$$\mathrm{also}\:\mathrm{see} \\ $$$$\mathrm{en}.\mathrm{wikipedia}.\mathrm{org}/\mathrm{wiki}/\mathrm{Polylogarithm} \\ $$$$ \\ $$$$\mathrm{trigonometric}\:\mathrm{integrals} \\ $$$$\mathrm{i}.\mathrm{e}.\:\int\frac{\mathrm{sin}\:{x}}{{x}}{dx} \\ $$$$\mathrm{en}.\mathrm{wikipedia}.\mathrm{org}/\mathrm{wiki}/\mathrm{Trigonometric\_integral} \\ $$

Question Number 44570 Answers: 1 Comments: 0

Question Number 44573 Answers: 1 Comments: 1

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