which best describes the graph of the cubic function (f(x)=x^{3}+x^{2}+x + 1)?\nas (x) increases, (y)…

which best describes the graph of the cubic function (f(x)=x^{3}+x^{2}+x + 1)?\nas (x) increases, (y) increases along the entire graph.\nas (x) increases, (y) increases, decreases, and then increases again.\nas (x) increases, (y) decreases, increases, and then decreases again.\nas (x) increases, (y) decreases along the entire graph.
Answer
Explanation:
Step1: Find the derivative
Differentiate $f(x)=x^{3}+x^{2}+x + 1$ using the power - rule. The derivative $f^\prime(x)=3x^{2}+2x + 1$.
Step2: Analyze the discriminant of the quadratic
For a quadratic function $ax^{2}+bx + c$ (here $a = 3$, $b = 2$, $c = 1$), the discriminant $\Delta=b^{2}-4ac$. Calculate $\Delta=(2)^{2}-4\times3\times1=4 - 12=-8<0$. And $a = 3>0$, so $f^\prime(x)>0$ for all real $x$.
Step3: Determine the behavior of the function
Since $f^\prime(x)>0$ for all real $x$, the function $y = f(x)$ is increasing for all real values of $x$. That is, as $x$ increases, $y$ increases along the entire graph.
Answer:
As $x$ increases, $y$ increases along the entire graph.