We'll determine x and y
intercepts.
The graph is intercepting x axis for y =
0.
Since y = f(x) => x^4 + x^3 - 13x^2 - x + 12 =
0
Since all the coefficients of the given function are
integer numbers, the roots of the function can be found among the divisors of the free
coefficient, 12.
We'll check if x = -4 is one of the
roots.
f(-4) = 256 - 64 - 208 + 4 +
12
f(-4) = 0 => x = -4 is one of the roots of the
function.
Applying long division, we'll get the quotient q
= x^3 - 3x^2 - x + 3.
We'll apply the reminder
theorem:
(x + 4)(x^3 - 3x^2 - x + 3) =
f(x)
If f(x) = 0 => (x + 4)(x^3 - 3x^2 - x +
3)
(x + 4)[x^2*(x - 3) - (x - 3)] =
0
(x + 4)(x - 3)(x^2 - 1) =
0
The difference of squares returns the
product:
x^2 - 1 = (x - 1)(x +
1)
(x + 4)(x - 3)(x - 1)(x + 1) =
0
We'll cancel each factor:
x
+ 4 = 0 => x = -4
x - 3 = 0 => x =
3
x - 1 = 0 => x = 1
x
+ 1 = 0 => x = -1
The graph is intercepting x axis
in the points: (4, 0), (3, 0), (-1, 0), (1, 0).
The graph
is intercepting y axis if x = 0.
f(0) = 0^4 + 0^3 – 13*0^2
– 0 + 12
f(0) = 12
The graph
is intercepting y axis in the point (0, 12).
The end
behavior of the function is found when is evaluated the limit of the function if x is
approaching to +/-infinite:
x approaches to +
infinite:
lim x^4 + x^3 - 13x^2 - x+12 = (+infinite)^4 =
+infinite
x approaches to -
infinite:
lim x^4 + x^3 - 13x^2 - x+12 = (-infinite)^4 =
+infinite
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