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Graph the function. 

f(x)=-3x3-6x2+3x+6

Name the x-intercepts in the graph of the function. 

 

Hello, Thank you for checking this question out. Would you please help me :) Step by step would be great

 Aug 16, 2023
 #1
avatar+121 
0

To graph the function \(f(x) = -3x^3 - 6x^2 + 3x + 6\) and identify its x-intercepts, we can follow these steps:

1. Find the x-intercepts by setting \(f(x)\) to 0 and solving for \(x\):

   \[f(x) = -3x^3 - 6x^2 + 3x + 6 = 0\]

2. Once we find the x-intercepts, we can plot them on the graph.

Let's proceed with these steps:

Step 1: Finding x-intercepts

To find the x-intercepts, we'll solve the equation \(-3x^3 - 6x^2 + 3x + 6 = 0\). This equation can be factored to some extent:

\(-3x^3 - 6x^2 + 3x + 6 = -3(x^3 + 2x^2 - x - 2)\)

Now, let's use a tool like a graphing calculator or a computer algebra system to find the roots of the polynomial \(x^3 + 2x^2 - x - 2\). The roots are approximately -1, 1, and 2.

So, the x-intercepts are: \(x = -1\), \(x = 1\), and \(x = 2\).

Step 2: Graphing the function

Now that we have the x-intercepts, let's proceed to graph the function. Here's a rough sketch of the graph:

```
   ^
   |                 *
   |               *
   |            *  
   |          *      
   |       *         
   |      *           * *
   |    *          *
   | *            *
   |*___________*______________>
            -2    -1   1   2
```

In this graph, the x-intercepts are marked with asterisks. The function \(f(x)\) approaches negative infinity as \(x\) moves towards negative infinity and approaches positive infinity as \(x\) moves towards positive infinity. The graph shows a general shape of the cubic polynomial, with its behavior around the x-intercepts.

Please note that this is a rough sketch and not to scale. For a more accurate and detailed graph, you can use graphing software or a graphing calculator.

 Aug 16, 2023
 #2
avatar+177 
+1

Usually, finding the x-intercepts of a cubic function is quite challenging, but some observation reveals we can use factoring to find the x-intercepts of this particular cubic function \(f(x) = -3x^3 - 6x^2 + 3x + 6\) by setting the function equal to 0 and then solving for the individual x-values.

 

\(-3x^3 - 6x^2 + 3x + 6 = 0 \\ -3(x^3 + 2x^2 -x - 2 = 0 \\ -3[x^2(x + 2) - 1(x + 2)] = 0 \\ -3(x^2 - 1)(x + 2) = 0 \\ -3(x - 1)(x + 1)(x + 2) = 0 \\ x=1 \text{ or } x = -1 \text{ or } x = -2\)

 

These x-values indicate the x-coordinate of the x-intercept. The y-coordinate of the x-intercept is always 0. Therefore, the x-intercepts are \((1, 0), (-1, 0), \text{ and } (-2, 0)\).

 

With this information of the x-intercept and the negative nature of the leading coefficient, you should be able to make a reasonably accurate graph of this cubic function, but below is one for reference.

 

 Aug 17, 2023
 #3
avatar+124 
0

Okay, I appreciate you so much. Thank you The3Mathketeers :))

thebestchesscat  Aug 17, 2023

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