Tap the blue points to see coordinates.
STEP 1:Find the x-intercepts
To find the x-intercepts solve, the equation $ \color{blue}{ 2x^3+x^2-25x+12 = 0 } $
The solutions of this equation are:
$$ \begin{matrix}x_1 = 3 & x_2 = -4 & x_3 = \dfrac{ 1 }{ 2 } \end{matrix} $$(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) = 2x^3+x^2-25x+12 } $, so:
$$ \text{Y inercept} = p(0) = 12 $$STEP 3:Find the end behavior
The end behavior of a polynomial is the same as the end behavior of a leading term.
$$ \lim_{x \to -\infty} \left( 2x^3+x^2-25x+12 \right) = \lim_{x \to -\infty} 2x^3 = \color{blue}{ -\infty } $$The graph starts in the lower-left corner.
$$ \lim_{x \to \infty} \left( 2x^3+x^2-25x+12 \right) = \lim_{x \to \infty} 2x^3 = \color{blue}{ \infty } $$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) $:
$$ p^{\prime} (x) = 6x^2+2x-25 $$The x coordinate of the turning points are located at the zeros of the first derivative
$$ p^{\prime} (x) = 0 $$ $$ \begin{matrix}x_1 = 1.8814 & x_2 = -2.2147 \end{matrix} $$(cleck here to see a explanation of how to solve the equation)
To find the y coordinates, substitute the above values into $ p(x) $
$$ \begin{aligned} \text{for } ~ x & = \color{blue}{ 1.8814 } \Rightarrow p\left(1.8814\right) = \color{orangered}{ -18.1763 }\\[1 em] \text{for } ~ x & = \color{blue}{ -2.2147 } \Rightarrow p\left(-2.2147\right) = \color{orangered}{ 50.5466 }\end{aligned} $$So the turning points are:
$$ \begin{matrix} \left( 1.8814, -18.1763 \right) & \left( -2.2147, 50.5466 \right)\end{matrix} $$STEP 5:Find the inflection points
The inflection points are located at zeroes of second derivative. The second derivative is $ p^{\prime \prime} (x) = 12x+2 $.
The zero of second derivative is
$$ \begin{matrix}x = -\dfrac{ 1 }{ 6 } \end{matrix} $$Substitute the x value into $ p(x) $ to get y coordinates
$$ \begin{aligned} \text{for } ~ x & = \color{blue}{ -\frac{ 1 }{ 6 } } \Rightarrow p\left(-\frac{ 1 }{ 6 }\right) = \color{orangered}{ \frac{ 437 }{ 27 } }\end{aligned} $$So the inflection point is:
$$ \begin{matrix} \left( -\dfrac{ 1 }{ 6 }, \dfrac{ 437 }{ 27 } \right)\end{matrix} $$