Mister Exam

Graphing y = x(x-2)/x-3

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The graph:

from to

Intersection points:

does show?

Piecewise:

The solution

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       x*(x - 2)    
f(x) = --------- - 3
           x        
$$f{\left(x \right)} = -3 + \frac{x \left(x - 2\right)}{x}$$
f = -3 + (x*(x - 2))/x
The graph of the function
The domain of the function
The points at which the function is not precisely defined:
$$x_{1} = 0$$
The points of intersection with the X-axis coordinate
Graph of the function intersects the axis X at f = 0
so we need to solve the equation:
$$-3 + \frac{x \left(x - 2\right)}{x} = 0$$
Solve this equation
The points of intersection with the axis X:

Analytical solution
$$x_{1} = 5$$
Numerical solution
$$x_{1} = 5$$
The points of intersection with the Y axis coordinate
The graph crosses Y axis when x equals 0:
substitute x = 0 to (x*(x - 2))/x - 3.
$$-3 + \frac{\left(-2\right) 0}{0}$$
The result:
$$f{\left(0 \right)} = \text{NaN}$$
- the solutions of the equation d'not exist
Extrema of the function
In order to find the extrema, we need to solve the equation
$$\frac{d}{d x} f{\left(x \right)} = 0$$
(the derivative equals zero),
and the roots of this equation are the extrema of this function:
$$\frac{d}{d x} f{\left(x \right)} = $$
the first derivative
$$- \frac{x - 2}{x} + \frac{2 x - 2}{x} = 0$$
Solve this equation
Solutions are not found,
function may have no extrema
Inflection points
Let's find the inflection points, we'll need to solve the equation for this
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = 0$$
(the second derivative equals zero),
the roots of this equation will be the inflection points for the specified function graph:
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = $$
the second derivative
$$\frac{1 + \frac{x - 2}{x} - \frac{2 \left(x - 1\right)}{x}}{x} = 0$$
Solve this equation
Solutions are not found,
maybe, the function has no inflections
Vertical asymptotes
Have:
$$x_{1} = 0$$
Horizontal asymptotes
Let’s find horizontal asymptotes with help of the limits of this function at x->+oo and x->-oo
$$\lim_{x \to -\infty}\left(-3 + \frac{x \left(x - 2\right)}{x}\right) = -\infty$$
Let's take the limit
so,
horizontal asymptote on the left doesn’t exist
$$\lim_{x \to \infty}\left(-3 + \frac{x \left(x - 2\right)}{x}\right) = \infty$$
Let's take the limit
so,
horizontal asymptote on the right doesn’t exist
Inclined asymptotes
Inclined asymptote can be found by calculating the limit of (x*(x - 2))/x - 3, divided by x at x->+oo and x ->-oo
$$\lim_{x \to -\infty}\left(\frac{-3 + \frac{x \left(x - 2\right)}{x}}{x}\right) = 1$$
Let's take the limit
so,
inclined asymptote equation on the left:
$$y = x$$
$$\lim_{x \to \infty}\left(\frac{-3 + \frac{x \left(x - 2\right)}{x}}{x}\right) = 1$$
Let's take the limit
so,
inclined asymptote equation on the right:
$$y = x$$
Even and odd functions
Let's check, whether the function even or odd by using relations f = f(-x) и f = -f(-x).
So, check:
$$-3 + \frac{x \left(x - 2\right)}{x} = - x - 5$$
- No
$$-3 + \frac{x \left(x - 2\right)}{x} = x + 5$$
- No
so, the function
not is
neither even, nor odd