Is the equation $y=\sqrt x$ a function?
10774
Why $f(x) = \sqrt{x}$ is a function?
38849
Solve $x^y \, = \, y^x$
157744
Cauchy's functional equation with composite function: $gf(x+y)=gf(x)+gf(y)$
58083
what can I say about the solution $y(x)$ of the ODE?
71049
Functional equation $f(xy)=f(x)+f(y)$ and continuity
133646
real analysis -functional equation
17175
Problem in solving functional equation $f(x^2 + yf(x)) = xf(x+y)$
98921
Does $y(y+1) \leq (x+1)^2$ imply $y(y-1) \leq x^2$?
116946
Ordinary differential equation $y'(t)=\sin(f(t,y))$
55175
Is the function $f(x) = x^2 - 2x$ one-to-one?
142845
is $y = \sqrt{x^2 + 1}− x$ a injective (one-to-one) function?
43667
Is $f(x,y(x))$ a function of two variables? If so, how is that possible?
145595
$\text{Let }y=\sqrt{5+\sqrt{5-\sqrt{5+\sqrt{5-...}}}} $, what is the nearest value of $y^2 - y$?
49794
Solve $f(x^2+y+f(y))=2y+f(x)^2$ over $\mathbb{R}$
134880
Is there a difference between $y(x)$ and $f(x)$
49705
Is $f(x,y)=(x+2y+y^2+|xy|, 2x+y+x^2+|xy|)$ differentiable?
105497
A function satisfying a series equation