To graph the function \( f(x) = 2(x-1)(x+3)^2 \) and understand its characteristics, we can analyze some key components, including its roots, behavior, and critical points.
Key Information
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End Behavior:
- As \( x \to -\infty \), \( f(x) \to -\infty \)
- As \( x \to +\infty \), \( f(x) \to +\infty \)
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Roots and Their Multiplicities:
- \( x = 1 \) (multiplicity 1) — This root indicates that the curve will cross the x-axis at this point.
- \( x = -3 \) (multiplicity 2) — Since this root has an even multiplicity, the graph touches the x-axis at this point and turns back without crossing.
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Leading Coefficient:
- The leading coefficient is positive (2), indicating that the ends of the graph will rise as \( x \to +\infty \) and drop as \( x \to -\infty \).
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Domain:
- The domain of \( f(x) \) is all real numbers: \( (-\infty, \infty) \)
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Range:
- The range of \( f(x) \) is all real numbers: \( (-\infty, \infty) \)
Key Points for Graphing
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Roots:
- \( (-3, 0) \): The graph touches the x-axis.
- \( (1, 0) \): The graph crosses the x-axis.
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Y-Intercept:
- To find the y-intercept, set \( x = 0 \): \[ f(0) = 2(0-1)(0+3)^2 = 2(-1)(9) = -18 \]
- So the y-intercept is \( (0, -18) \).
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Critical Points:
- Calculate the derivative \( f'(x) \) to find local maxima or minima.
- Use the product rule to differentiate if necessary, but we can also inspect the graph around the roots above.
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Behavior Between Roots:
- For \( x < -3 \): As \( x \) approaches \( -3 \), \( f(x) \) is negative and decreases to approach 0.
- For \( -3 < x < 1 \): The function is negative, moving from 0 (at -3) to a minimum before crossing at (1,0).
- For \( x > 1 \): The function increases and rises positively towards infinity.
Graphing
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Plot the key coordinates:
- Roots: \( (-3,0) \), \( (1,0) \)
- Y-Intercept: \( (0, -18) \)
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Sketch the overall shape:
- Starts from low (-∞) as \( x \) approaches \( -\infty \).
- Rises towards \( (-3,0) \), touches and turns back down.
- Falls to a minimum point and crosses the x-axis at \( (1, 0) \).
- Finally, rises to infinity as \( x \) goes to +∞.
Summary
Using the information above, you now have the key coordinates, behavior at infinity, critical points, and a detailed description of where to plot in order to graph the function accurately. Note that the curve will have a "bounce back" effect at \( (-3, 0) \) due to the multiplicity of 2, and will cross the x-axis at \( (1, 0) \). You can use graphing software or graphing calculators to visualize this function accurately.