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Question Number 77323    Answers: 0   Comments: 2

Question Number 77314    Answers: 0   Comments: 6

Question Number 77313    Answers: 0   Comments: 4

x + y + z = 1 x^2 + y^2 + z^2 = 2 x^3 + y^3 + z^3 = 3 find x^8 + y^8 +z^8

$$\mathrm{x}\:+\:\mathrm{y}\:+\:\mathrm{z}\:=\:\mathrm{1} \\ $$$$\mathrm{x}^{\mathrm{2}} \:+\:\mathrm{y}^{\mathrm{2}} \:+\:\mathrm{z}^{\mathrm{2}} \:=\:\mathrm{2} \\ $$$$\mathrm{x}^{\mathrm{3}} \:+\:\mathrm{y}^{\mathrm{3}} \:+\:\mathrm{z}^{\mathrm{3}} \:=\:\mathrm{3} \\ $$$$ \\ $$$$\mathrm{find}\:\mathrm{x}^{\mathrm{8}} \:+\:\mathrm{y}^{\mathrm{8}} \:+\mathrm{z}^{\mathrm{8}} \\ $$

Question Number 77309    Answers: 1   Comments: 4

Question Number 77297    Answers: 1   Comments: 0

If y(x) is a solution of the differential equation (((2+sinx)/(1+y)))(dy/dx)=−cosx and y(0)=1, then find the value of y(π/2) ?

$$\mathrm{If}\:\mathrm{y}\left(\mathrm{x}\right)\:\mathrm{is}\:\mathrm{a}\:\mathrm{solution}\:\mathrm{of}\:\mathrm{the}\:\mathrm{differential} \\ $$$$\mathrm{equation}\:\left(\frac{\mathrm{2}+\mathrm{sinx}}{\mathrm{1}+\mathrm{y}}\right)\frac{\mathrm{dy}}{\mathrm{dx}}=−\mathrm{cosx}\:\mathrm{and} \\ $$$$\mathrm{y}\left(\mathrm{0}\right)=\mathrm{1},\:\mathrm{then}\:\mathrm{find}\:\mathrm{the}\:\mathrm{value}\:\mathrm{of} \\ $$$$\mathrm{y}\left(\pi/\mathrm{2}\right)\:\:? \\ $$

Question Number 77296    Answers: 0   Comments: 4

Determiner et construire l.ensemble des points M tel que: 3MA^2 +MB^2 −MC^2 =−42 Le plan est muni d.un repere orthonorme (O,I,J) A(1,2) B(−2,3) C(1,9). on considere que O=barycentre{(A,3);(B;1);(C;−1)}

$$\mathrm{Determiner}\:\mathrm{et}\:\mathrm{construire}\:\mathrm{l}.\mathrm{ensemble} \\ $$$$\mathrm{des}\:\mathrm{points}\:\mathrm{M}\:\mathrm{tel}\:\mathrm{que}: \\ $$$$\mathrm{3MA}^{\mathrm{2}} +\mathrm{MB}^{\mathrm{2}} −\mathrm{MC}^{\mathrm{2}} =−\mathrm{42} \\ $$$$\mathrm{Le}\:\mathrm{plan}\:\mathrm{est}\:\mathrm{muni}\:\mathrm{d}.\mathrm{un}\:\mathrm{repere}\: \\ $$$$\mathrm{orthonorme}\:\left(\mathrm{O},\mathrm{I},\mathrm{J}\right) \\ $$$$\mathrm{A}\left(\mathrm{1},\mathrm{2}\right)\:\:\:\mathrm{B}\left(−\mathrm{2},\mathrm{3}\right)\:\:\mathrm{C}\left(\mathrm{1},\mathrm{9}\right). \\ $$$$\mathrm{on}\:\mathrm{considere}\:\mathrm{que}\: \\ $$$$\mathrm{O}=\mathrm{barycentre}\left\{\left(\mathrm{A},\mathrm{3}\right);\left(\mathrm{B};\mathrm{1}\right);\left(\mathrm{C};−\mathrm{1}\right)\right\} \\ $$

Question Number 77294    Answers: 1   Comments: 0

f(x)=x^3 −27x Find intervals where given fuction ii is 1.increasing 2.decreasing 3 concave up and down 4 point of inflection

$${f}\left({x}\right)={x}^{\mathrm{3}} −\mathrm{27}{x} \\ $$$${Find}\:{intervals}\:{where}\:{given}\:{fuction}\:{ii} \\ $$$${is} \\ $$$$\mathrm{1}.{increasing} \\ $$$$\mathrm{2}.{decreasing} \\ $$$$\mathrm{3}\:{concave}\:{up}\:{and}\:{down} \\ $$$$\mathrm{4}\:{point}\:{of}\:{inflection} \\ $$

Question Number 77290    Answers: 2   Comments: 3

∫ (√(x^3 + x^4 )) dx

$$\int\:\sqrt{\mathrm{x}^{\mathrm{3}} \:+\:\mathrm{x}^{\mathrm{4}} }\:\:\mathrm{dx} \\ $$

Question Number 77285    Answers: 1   Comments: 0

how to find the Fourier series of f(x) = x , 0 < x<(1/8)

$$\mathrm{how}\:\mathrm{to}\:\mathrm{find}\:\mathrm{the}\: \\ $$$$\mathrm{Fourier}\:\mathrm{series}\:\mathrm{of}\:\mathrm{f}\left(\mathrm{x}\right)\:=\:\mathrm{x}\:,\:\mathrm{0}\:<\:\mathrm{x}<\frac{\mathrm{1}}{\mathrm{8}} \\ $$

Question Number 77280    Answers: 0   Comments: 2

Question Number 77279    Answers: 0   Comments: 0

Question Number 77272    Answers: 1   Comments: 3

given T.ABCD is pyramid with AB = BC = 8 and AT = 6 . P is midpoint BC, Q is midpoint AT. If α is the angle between TP and PQ then cos α is ...

$$\mathrm{given}\:\mathrm{T}.\mathrm{ABCD}\:\mathrm{is}\:\mathrm{pyramid}\: \\ $$$$\mathrm{with}\:\mathrm{AB}\:=\:\mathrm{BC}\:=\:\mathrm{8}\:\mathrm{and}\:\mathrm{AT}\:=\:\mathrm{6} \\ $$$$\:.\:\mathrm{P}\:\mathrm{is}\:\mathrm{midpoint}\:\mathrm{BC},\:\mathrm{Q}\:\mathrm{is}\:\mathrm{midpoint}\:\mathrm{AT}. \\ $$$$\mathrm{If}\:\alpha\:\mathrm{is}\:\mathrm{the}\:\mathrm{angle}\:\mathrm{between}\:\mathrm{TP}\:\mathrm{and} \\ $$$$\mathrm{PQ}\:\mathrm{then}\:\mathrm{cos}\:\alpha\:\mathrm{is}\:... \\ $$

Question Number 77271    Answers: 0   Comments: 0

given the function y = (1/(x^2 +1)). The tangent equation of the curve with the smallest gradient is ..

$$\mathrm{given}\:\mathrm{the}\:\mathrm{function} \\ $$$$\mathrm{y}\:=\:\frac{\mathrm{1}}{\mathrm{x}^{\mathrm{2}} +\mathrm{1}}.\:\mathrm{The}\:\mathrm{tangent}\:\mathrm{equation} \\ $$$$\mathrm{of}\:\mathrm{the}\:\mathrm{curve}\:\mathrm{with}\:\mathrm{the}\:\mathrm{smallest}\: \\ $$$$\mathrm{gradient}\:\mathrm{is}\:.. \\ $$

Question Number 77269    Answers: 0   Comments: 1

what is ∫ (1/(tan^3 (x^2 −1))) dx ?

$${what}\:{is}\:\int\:\frac{\mathrm{1}}{\mathrm{tan}\:^{\mathrm{3}} \left({x}^{\mathrm{2}} −\mathrm{1}\right)}\:{dx}\:? \\ $$

Question Number 77252    Answers: 1   Comments: 2

Question Number 77242    Answers: 1   Comments: 3

prove that ∫_0 ^a (√(2+(a/x)−2(√(a/x)) ))dx=a[(1/(√2))ln((√2)+1)+1]

$${prove}\:{that} \\ $$$$\:\int_{\mathrm{0}} ^{{a}} \sqrt{\mathrm{2}+\frac{{a}}{{x}}−\mathrm{2}\sqrt{\frac{{a}}{{x}}}\:}{dx}={a}\left[\frac{\mathrm{1}}{\sqrt{\mathrm{2}}}{ln}\left(\sqrt{\mathrm{2}}+\mathrm{1}\right)+\mathrm{1}\right] \\ $$

Question Number 77232    Answers: 1   Comments: 0

∫_0 ^1 ln ( (√x) + (√(1−x)) ) dx = ?

$$\underset{\mathrm{0}} {\int}\overset{\mathrm{1}} {\:}\:\mathrm{ln}\:\left(\:\sqrt{{x}}\:+\:\sqrt{\mathrm{1}−{x}}\:\right)\:{dx}\:\:=\:\:? \\ $$

Question Number 77230    Answers: 1   Comments: 0

An astromer finds a new absorption line with λ=164.1nm in the ultraviolet region of the sun′s continuous spectrum. He attributes the line to hydrogen′s Layman series. Is he right? Justify your answer. please help.

$$\mathrm{An}\:\mathrm{astromer}\:\mathrm{finds}\:\mathrm{a}\:\mathrm{new}\:\mathrm{absorption}\: \\ $$$$\mathrm{line}\:\mathrm{with}\:\lambda=\mathrm{164}.\mathrm{1nm}\:\mathrm{in}\:\mathrm{the}\:\mathrm{ultraviolet} \\ $$$$\mathrm{region}\:\mathrm{of}\:\mathrm{the}\:\mathrm{sun}'\mathrm{s}\:\mathrm{continuous}\:\mathrm{spectrum}. \\ $$$$\mathrm{He}\:\mathrm{attributes}\:\mathrm{the}\:\mathrm{line}\:\mathrm{to}\:\mathrm{hydrogen}'\mathrm{s}\: \\ $$$$\mathrm{Layman}\:\mathrm{series}.\:\mathrm{Is}\:\mathrm{he}\:\mathrm{right}?\:\mathrm{Justify} \\ $$$$\mathrm{your}\:\mathrm{answer}. \\ $$$$ \\ $$$$\boldsymbol{\mathrm{please}}\:\boldsymbol{\mathrm{help}}. \\ $$

Question Number 77229    Answers: 1   Comments: 1

Question Number 77221    Answers: 2   Comments: 0

∫ (((√(2+x)) dx)/(√x^5 )) = ?

$$\int\:\frac{\sqrt{\mathrm{2}+{x}}\:{dx}}{\sqrt{{x}^{\mathrm{5}} }}\:=\:? \\ $$

Question Number 77219    Answers: 1   Comments: 0

if log_9 (a)=log_4 (a+b)=log_6 (b) what is (a/b) ?

$${if}\:\mathrm{log}_{\mathrm{9}} \left({a}\right)=\mathrm{log}_{\mathrm{4}} \left({a}+{b}\right)=\mathrm{log}_{\mathrm{6}} \left({b}\right)\: \\ $$$${what}\:{is}\:\frac{{a}}{{b}}\:? \\ $$

Question Number 77218    Answers: 1   Comments: 0

what is solution in R ((sin (x)−∣x+2∣)/(x^2 −4x−5))≥0 ?

$${what}\:{is}\:{solution}\:{in}\:\mathbb{R}\: \\ $$$$\frac{\mathrm{sin}\:\left({x}\right)−\mid{x}+\mathrm{2}\mid}{{x}^{\mathrm{2}} −\mathrm{4}{x}−\mathrm{5}}\geqslant\mathrm{0}\:?\: \\ $$

Question Number 77216    Answers: 0   Comments: 0

Question Number 77213    Answers: 0   Comments: 3

Question Number 77208    Answers: 0   Comments: 1

some thoughts on this forum... we cannot solve the unanswered questions much greater mathematicians haven′t been able to solve yet thus it makes absolutely no sense to post them here also it makes no sense to post problems from books or from the www if you don′t have the foggiest idea of their meaning or how to solve them. it might be fun for us to solve some of them but mostly it′s like casting pearls...

$$\mathrm{some}\:\mathrm{thoughts}\:\mathrm{on}\:\mathrm{this}\:\mathrm{forum}... \\ $$$$\mathrm{we}\:\mathrm{cannot}\:\mathrm{solve}\:\mathrm{the}\:\mathrm{unanswered}\:\mathrm{questions} \\ $$$$\mathrm{much}\:\mathrm{greater}\:\mathrm{mathematicians}\:\mathrm{haven}'\mathrm{t}\:\mathrm{been} \\ $$$$\mathrm{able}\:\mathrm{to}\:\mathrm{solve}\:\mathrm{yet} \\ $$$$\mathrm{thus}\:\mathrm{it}\:\mathrm{makes}\:\mathrm{absolutely}\:\mathrm{no}\:\mathrm{sense}\:\mathrm{to}\:\mathrm{post} \\ $$$$\mathrm{them}\:\mathrm{here} \\ $$$$\mathrm{also}\:\mathrm{it}\:\mathrm{makes}\:\mathrm{no}\:\mathrm{sense}\:\mathrm{to}\:\mathrm{post}\:\mathrm{problems}\:\mathrm{from} \\ $$$$\mathrm{books}\:\mathrm{or}\:\mathrm{from}\:\mathrm{the}\:\mathrm{www}\:\mathrm{if}\:\mathrm{you}\:\mathrm{don}'\mathrm{t}\:\mathrm{have}\:\mathrm{the} \\ $$$$\mathrm{foggiest}\:\mathrm{idea}\:\mathrm{of}\:\mathrm{their}\:\mathrm{meaning}\:\mathrm{or}\:\mathrm{how}\:\mathrm{to}\:\mathrm{solve} \\ $$$$\mathrm{them}.\:\mathrm{it}\:\mathrm{might}\:\mathrm{be}\:\mathrm{fun}\:\mathrm{for}\:\mathrm{us}\:\mathrm{to}\:\mathrm{solve}\:\mathrm{some}\:\mathrm{of} \\ $$$$\mathrm{them}\:\mathrm{but}\:\mathrm{mostly}\:\mathrm{it}'\mathrm{s}\:\mathrm{like}\:\mathrm{casting}\:\mathrm{pearls}... \\ $$

Question Number 77204    Answers: 0   Comments: 2

is there a general solution for the equation x[x[x[x...]]]_(n times x) =m with x>0, m>0.

$${is}\:{there}\:{a}\:{general}\:{solution}\:{for} \\ $$$${the}\:{equation} \\ $$$$\underset{{n}\:{times}\:{x}} {\boldsymbol{{x}}\left[\boldsymbol{{x}}\left[\boldsymbol{{x}}\left[\boldsymbol{{x}}...\right]\right]\right]}=\boldsymbol{{m}} \\ $$$${with}\:{x}>\mathrm{0},\:{m}>\mathrm{0}. \\ $$

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