Mister Exam

Graphing y = (3x+8):4

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The graph:

from to

Intersection points:

does show?

Piecewise:

The solution

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       3*x + 8
f(x) = -------
          4   
f(x)=3x+84f{\left(x \right)} = \frac{3 x + 8}{4}
f = (3*x + 8)/4
The graph of the function
02468-8-6-4-2-1010-2020
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:
3x+84=0\frac{3 x + 8}{4} = 0
Solve this equation
The points of intersection with the axis X:

Analytical solution
x1=83x_{1} = - \frac{8}{3}
Numerical solution
x1=2.66666666666667x_{1} = -2.66666666666667
The points of intersection with the Y axis coordinate
The graph crosses Y axis when x equals 0:
substitute x = 0 to (3*x + 8)/4.
03+84\frac{0 \cdot 3 + 8}{4}
The result:
f(0)=2f{\left(0 \right)} = 2
The point:
(0, 2)
Extrema of the function
In order to find the extrema, we need to solve the equation
ddxf(x)=0\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:
ddxf(x)=\frac{d}{d x} f{\left(x \right)} =
the first derivative
34=0\frac{3}{4} = 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
d2dx2f(x)=0\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:
d2dx2f(x)=\frac{d^{2}}{d x^{2}} f{\left(x \right)} =
the second derivative
0=00 = 0
Solve this equation
Solutions are not found,
maybe, the function has no inflections
Horizontal asymptotes
Let’s find horizontal asymptotes with help of the limits of this function at x->+oo and x->-oo
limx(3x+84)=\lim_{x \to -\infty}\left(\frac{3 x + 8}{4}\right) = -\infty
Let's take the limit
so,
horizontal asymptote on the left doesn’t exist
limx(3x+84)=\lim_{x \to \infty}\left(\frac{3 x + 8}{4}\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 (3*x + 8)/4, divided by x at x->+oo and x ->-oo
limx(3x+84x)=34\lim_{x \to -\infty}\left(\frac{3 x + 8}{4 x}\right) = \frac{3}{4}
Let's take the limit
so,
inclined asymptote equation on the left:
y=3x4y = \frac{3 x}{4}
limx(3x+84x)=34\lim_{x \to \infty}\left(\frac{3 x + 8}{4 x}\right) = \frac{3}{4}
Let's take the limit
so,
inclined asymptote equation on the right:
y=3x4y = \frac{3 x}{4}
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:
3x+84=23x4\frac{3 x + 8}{4} = 2 - \frac{3 x}{4}
- No
3x+84=3x42\frac{3 x + 8}{4} = \frac{3 x}{4} - 2
- No
so, the function
not is
neither even, nor odd