Sketch the graph of the polynomial function $$ p(x) = x^6+3x^5+2x^2 $$

Tap the blue points to see coordinates.

STEP 1:Find the x-intercepts

To find the x-intercepts solve, the equation $ \color{blue}{ x^6+3x^5+2x^2 = 0 } $

The solutions of this equation are:

$$ \begin{matrix}x_1 = 0 & x_2 = -1 & x_3 = -2.9196 \end{matrix} $$

(you can use the step-by-step polynomial equation solver to see a detailed explanation of how to solve the equation)

STEP 2:Find the y-intercepts

To find the y-intercepts, substitute $ x = 0 $ into $ \color{blue}{ p(x) = x^6+3x^5+2x^2 } $, so:

$$ \text{Y inercept} = p(0) = 0 $$

STEP 3:Find the end behavior

The end behavior of a polynomial is the same as the end behavior of a leading term.

$$ \lim_{x \to -\infty} \left( x^6+3x^5+2x^2 \right) = \lim_{x \to -\infty} x^6 = \color{blue}{ \infty } $$

The graph starts in the upper-left corner.

$$ \lim_{x \to \infty} \left( x^6+3x^5+2x^2 \right) = \lim_{x \to \infty} x^6 = \color{blue}{ \infty } $$

The graph ends in the upper-right corner.

STEP 4:Find the turning points

To determine the turning points, we need to find the first derivative of $ p(x) $:

$$ p^{\prime} (x) = 6x^5+15x^4+4x $$

The x coordinate of the turning points are located at the zeros of the first derivative

$$ p^{\prime} (x) = 0 $$ $$ \begin{matrix}x_1 = 0 & x_2 = -0.721 & x_3 = -2.4549 \end{matrix} $$

(cleck here to see a explanation of how to solve the equation)

To find the y coordinates, substitute the above values into $ p(x) $

$$ \begin{aligned} \text{for } ~ x & = \color{blue}{ 0 } \Rightarrow p\left(0\right) = \color{orangered}{ 0 }\\[1 em] \text{for } ~ x & = \color{blue}{ -0.721 } \Rightarrow p\left(-0.721\right) = \color{orangered}{ 0.5956 }\\[1 em] \text{for } ~ x & = \color{blue}{ -2.4549 } \Rightarrow p\left(-2.4549\right) = \color{orangered}{ -36.5479 }\end{aligned} $$

So the turning points are:

$$ \begin{matrix} \left( 0, 0 \right) & \left( -0.721, 0.5956 \right) & \left( -2.4549, -36.5479 \right)\end{matrix} $$

STEP 5:Find the inflection points

The inflection points are located at zeroes of second derivative. The second derivative is $ p^{\prime \prime} (x) = 30x^4+60x^3+4 $.

The zeros of second derivative are

$$ \begin{matrix}x_1 = -0.4405 & x_2 = -1.9829 \end{matrix} $$

Substitute the x values into $ p(x) $ to get y coordinates

$$ \begin{aligned} \text{for } ~ x & = \color{blue}{ -0.4405 } \Rightarrow p\left(-0.4405\right) = \color{orangered}{ 0.3457 }\\[1 em] \text{for } ~ x & = \color{blue}{ -1.9829 } \Rightarrow p\left(-1.9829\right) = \color{orangered}{ -23.3156 }\end{aligned} $$

So the inflection points are:

$$ \begin{matrix} \left( -0.4405, 0.3457 \right) & \left( -1.9829, -23.3156 \right)\end{matrix} $$

Graphing Polynomials