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show that the variance δ^2 of a set of observations x_1 ,x_2 ,...x_n with mean x^_ can be expressed in the form δ^2 = ((Σ_(i=1) ^n x_i ^2 )/n) − x^ ^(2 )

$$\mathrm{show}\:\mathrm{that}\:\mathrm{the}\:\mathrm{variance}\:\delta^{\mathrm{2}} \:\mathrm{of}\:\mathrm{a}\:\mathrm{set}\:\mathrm{of}\:\mathrm{observations}\:{x}_{\mathrm{1}} ,{x}_{\mathrm{2}} ,...{x}_{{n}} \:\mathrm{with}\:\mathrm{mean} \\ $$$$\overset{\_} {{x}}\:\mathrm{can}\:\mathrm{be}\:\mathrm{expressed}\:\mathrm{in}\:\mathrm{the}\:\mathrm{form}\:\:\delta^{\mathrm{2}} \:=\:\frac{\underset{{i}=\mathrm{1}} {\overset{{n}} {\sum}}{x}_{{i}} ^{\mathrm{2}} }{{n}}\:−\:\bar {{x}}\:^{\mathrm{2}\:} \\ $$

Question Number 88559 Answers: 0 Comments: 1

∫_((−π)/6) ^((3π)/4) ((√(tanx))/(1+(√(tanx))))dx

$$\int_{\frac{−\pi}{\mathrm{6}}} ^{\frac{\mathrm{3}\pi}{\mathrm{4}}} \frac{\sqrt{{tanx}}}{\mathrm{1}+\sqrt{{tanx}}}{dx} \\ $$

Question Number 88494 Answers: 0 Comments: 2

∫ (√(cos(x))) dx

$$\int\:\sqrt{\mathrm{cos}\left(\mathrm{x}\right)}\:\:\mathrm{dx} \\ $$

Question Number 88436 Answers: 0 Comments: 0

show that (for e>1) the equation of a hyperbola with focus (±ae,0) and directrix x = (a/e) is (x^2 /a^2 ) − (y^2 /b^2 ) hence find an equation for the eccencitrity of the hyperbola

$$\:\mathrm{show}\:\mathrm{that}\:\left(\mathrm{for}\:{e}>\mathrm{1}\right)\:\mathrm{the}\:\mathrm{equation}\:\mathrm{of}\:\mathrm{a}\:\mathrm{hyperbola}\:\mathrm{with}\: \\ $$$$\mathrm{focus}\:\:\left(\pm{ae},\mathrm{0}\right)\:\mathrm{and}\:\mathrm{directrix}\:\:{x}\:=\:\frac{{a}}{{e}}\:\mathrm{is}\:\frac{{x}^{\mathrm{2}} }{{a}^{\mathrm{2}} }\:−\:\frac{{y}^{\mathrm{2}} }{{b}^{\mathrm{2}} } \\ $$$$\:\:\:\mathrm{hence}\:\mathrm{find}\:\mathrm{an}\:\mathrm{equation}\:\mathrm{for}\:\mathrm{the}\:\mathrm{eccencitrity}\:\mathrm{of}\: \\ $$$$\mathrm{the}\:\mathrm{hyperbola} \\ $$

Question Number 88434 Answers: 0 Comments: 2

find the partial derivatives of first and second order for the function f(x,y) = x^3 y + 3xy + y^4

$$\mathrm{find}\:\mathrm{the}\:\mathrm{partial}\:\mathrm{derivatives}\:\mathrm{of}\:\mathrm{first}\:\mathrm{and}\:\mathrm{second}\:\mathrm{order} \\ $$$$\mathrm{for}\:\mathrm{the}\:\mathrm{function} \\ $$$$\:{f}\left({x},{y}\right)\:=\:{x}^{\mathrm{3}} {y}\:+\:\mathrm{3}{xy}\:+\:{y}^{\mathrm{4}} \\ $$

Question Number 88417 Answers: 0 Comments: 1

e^(−z) _1 f_1 (a;b;z)=((Γ(b))/(Γ(b−a))) G_(1,2) ^(1,1) (z∣_(0,1−b) ^(a−b+1) )

$${e}^{−{z}} \:_{\mathrm{1}} {f}_{\mathrm{1}} \left({a};{b};{z}\right)=\frac{\Gamma\left({b}\right)}{\Gamma\left({b}−{a}\right)}\:{G}_{\mathrm{1},\mathrm{2}} ^{\mathrm{1},\mathrm{1}} \left({z}\mid_{\mathrm{0},\mathrm{1}−{b}} ^{{a}−{b}+\mathrm{1}} \right) \\ $$

Question Number 88339 Answers: 3 Comments: 3

∫( (√(tan x )) + (√(cot x)) )dx = ?

$$\:\int\left(\:\sqrt{\mathrm{tan}\:{x}\:}\:+\:\sqrt{\mathrm{cot}\:{x}}\:\right){dx}\:=\:? \\ $$

Question Number 88263 Answers: 1 Comments: 1

prove that ∣((e^z −e^(−z) )/2)∣^2 +cos^2 y=sinh^2 x when z=x+iy

$${prove}\:{that}\: \\ $$$$\mid\frac{{e}^{{z}} −{e}^{−{z}} }{\mathrm{2}}\mid^{\mathrm{2}} +{cos}^{\mathrm{2}} {y}={sinh}^{\mathrm{2}} {x}\:\:\:\:\:{when}\:{z}={x}+{iy} \\ $$$$ \\ $$

Question Number 88236 Answers: 1 Comments: 0

Evaluate ∫(((27)/(x^3 −6)))^(1/3) dx

$$\:\mathrm{Evaluate}\:\:\int\sqrt[{\mathrm{3}}]{\frac{\mathrm{27}}{{x}^{\mathrm{3}} −\mathrm{6}}}\:{dx}\: \\ $$

Question Number 88235 Answers: 0 Comments: 1

find a maclaurine series solution to the differential equation up to the term in x^4 . (dy/dx) − x = xy if y = 1 when x = 0.

$$\:\mathrm{find}\:\mathrm{a}\:\mathrm{maclaurine}\:\mathrm{series}\:\mathrm{solution}\:\mathrm{to}\:\mathrm{the}\:\mathrm{differential}\:\mathrm{equation} \\ $$$$\mathrm{up}\:\mathrm{to}\:\mathrm{the}\:\mathrm{term}\:\mathrm{in}\:{x}^{\mathrm{4}} . \\ $$$$\:\frac{{dy}}{{dx}}\:−\:{x}\:=\:{xy}\:\:\:\mathrm{if}\:\:{y}\:=\:\mathrm{1}\:\mathrm{when}\:{x}\:=\:\mathrm{0}. \\ $$

Question Number 88169 Answers: 1 Comments: 2

find Laplace transform t^3 . cos 4t

$$\mathrm{find}\:\mathrm{Laplace}\:\mathrm{transform}\: \\ $$$$\mathrm{t}^{\mathrm{3}} .\:\mathrm{cos}\:\:\mathrm{4t} \\ $$

Question Number 87870 Answers: 0 Comments: 0

x amd y are imtegers. how many possible solitions do the eqiation has x^2 −10y^2 = ±1

$$\boldsymbol{\mathrm{x}}\:\boldsymbol{\mathrm{amd}}\:\boldsymbol{\mathrm{y}}\:\boldsymbol{\mathrm{are}}\:\boldsymbol{\mathrm{imtegers}}. \\ $$$$\boldsymbol{\mathrm{how}}\:\boldsymbol{\mathrm{many}}\:\boldsymbol{\mathrm{possible}}\:\boldsymbol{\mathrm{solitions}}\:\boldsymbol{\mathrm{do}}\:\boldsymbol{\mathrm{the}}\:\boldsymbol{\mathrm{eqiation}}\:\boldsymbol{\mathrm{has}} \\ $$$$\boldsymbol{\mathrm{x}}^{\mathrm{2}} −\mathrm{10}\boldsymbol{\mathrm{y}}^{\mathrm{2}} \:=\:\pm\mathrm{1} \\ $$

Question Number 87862 Answers: 0 Comments: 3

Evaluate ∫_(−1) ^1 (1/(x−1)) dx

$$\mathrm{Evaluate}\:\:\:\:\overset{\mathrm{1}} {\int}_{−\mathrm{1}} \frac{\mathrm{1}}{{x}−\mathrm{1}}\:{dx}\: \\ $$

Question Number 87861 Answers: 0 Comments: 4

∫_0 ^(π/4) tanh 2x dx

$$\underset{\mathrm{0}} {\overset{\frac{\pi}{\mathrm{4}}} {\int}}\:\mathrm{tanh}\:\mathrm{2}{x}\:{dx} \\ $$

Question Number 87754 Answers: 0 Comments: 0

Given that forces F_(1 ) and F_2 position vectors r_(1 ) and r_2 F_1 = (2i + 3j)N r_1 = i + 2j F_2 = (αi−7j) N r_2 = 3i + 4j Given that these system of forces form a couple find the value of α.

$$\mathrm{Given}\:\mathrm{that}\:\mathrm{forces}\:\mathrm{F}_{\mathrm{1}\:} \:\mathrm{and}\:\mathrm{F}_{\mathrm{2}} \:\mathrm{position}\:\mathrm{vectors}\:\mathrm{r}_{\mathrm{1}\:} \mathrm{and}\:\mathrm{r}_{\mathrm{2}} \\ $$$$\:\:\boldsymbol{\mathrm{F}}_{\mathrm{1}} \:=\:\left(\mathrm{2}\boldsymbol{{i}}\:+\:\mathrm{3}\boldsymbol{{j}}\right)\mathrm{N}\:\:\:\:\:\:\:\:\boldsymbol{\mathrm{r}}_{\mathrm{1}} =\:\boldsymbol{\mathrm{i}}\:+\:\mathrm{2}\boldsymbol{\mathrm{j}} \\ $$$$\:\:\:\boldsymbol{\mathrm{F}}_{\mathrm{2}} \:=\:\left(\alpha\boldsymbol{{i}}−\mathrm{7}\boldsymbol{{j}}\right)\:\mathrm{N}\:\:\:\:\:\:\:\:\boldsymbol{\mathrm{r}}_{\mathrm{2}} \:=\:\mathrm{3}\boldsymbol{\mathrm{i}}\:+\:\mathrm{4}\boldsymbol{\mathrm{j}} \\ $$$$\mathrm{Given}\:\mathrm{that}\:\mathrm{these}\:\mathrm{system}\:\mathrm{of}\:\mathrm{forces}\:\mathrm{form}\:\mathrm{a}\:\mathrm{couple} \\ $$$$\:\mathrm{find}\:\mathrm{the}\:\mathrm{value}\:\mathrm{of}\:\alpha. \\ $$

Question Number 87752 Answers: 1 Comments: 0

A particle exhibits simple hamornic motion such that (d^2 x/dt^2 ) + 4x = 0 Calculate the period of the ocsillation

$$\mathrm{A}\:\mathrm{particle}\:\mathrm{exhibits}\:\mathrm{simple}\:\mathrm{hamornic}\:\mathrm{motion}\:\mathrm{such}\:\mathrm{that} \\ $$$$\:\:\frac{{d}^{\mathrm{2}} {x}}{{dt}^{\mathrm{2}} }\:+\:\mathrm{4}{x}\:=\:\mathrm{0} \\ $$$$\:\mathrm{Calculate}\:\mathrm{the}\:\mathrm{period}\:\mathrm{of}\:\mathrm{the}\:\mathrm{ocsillation}\: \\ $$

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