Functions defined parametrically

[5/100%]
Show
LaTeX

The function y=y(x)y=y(x) is given by the equations:

x=arctg⁡t,y=arcctg⁡t(−∞<t<+∞), x=\operatorname {arctg}t , \quad y=\operatorname {arcctg}t \quad (-\infty <t<+\infty ) ,

find this function. On what domain is this function defined?

?

Let

x=ch⁡t,y=sh⁡t(−∞<t<+∞). x=\operatorname {ch}t , \quad y=\operatorname {sh}t \quad (-\infty <t<+\infty ) .

Over what domain of variation of the parameter tt can the variable yy be regarded as a single-valued function of the variable xx? Find the expression for yy on each such domain.

?

What is the necessary and sufficient condition for the system of equations

x=φ(t),y=ϕ(t) x=\varphi (t) , \quad y=\phi (t)

to define yy as a single-valued function of xx?

?

Under what conditions do the two systems of equations

x=φ(t),y=ϕ(t)(a<t<b) x=\varphi (t) , \quad y=\phi (t) \quad (a<t<b)

and

x=φ[χ(τ)],y=ϕ[χ(τ)](α<τ<β) x=\varphi \left[\chi (\tau )\right] , \quad y=\phi \left[\chi (\tau )\right] \quad (\alpha <\tau <\beta )

define the same function y=y(x)y=y(x)?

?

Let the functions φ(x)\varphi (x) and ϕ(x)\phi (x) be defined and continuous on the interval (a,b)(a,b), and let

A=inf⁡a<x<bφ(x),B=sup⁡a<x<bφ(x). A=\inf _{a<x<b}\varphi (x) , \quad B=\sup _{a<x<b}\varphi (x) .

Under what circumstances does there exist a single-valued function f(x)f(x) defined on the interval (A,B)(A,B) such that, for a<x<ba<x<b, ϕ(x)=f[φ(x)]\phi (x)=f\left[\varphi (x)\right]?

?

References

[Dem97] Demidovich B.P. Сборник задач и упражнений по математическому анализу. 13-е изд., Издательство Московского университета / Издательство "ЧеРо", 1997.