Chapter 5: Problem 5
Find the area under the curve \(y=f(x)\) over the stated interval. $$ f(x)=x^{3} ;[2,3] $$
Short Answer
Expert verified
The area is \(\frac{65}{4}\) square units.
Step by step solution
01
Identify the function and interval
The function given is \(f(x) = x^3\) and the interval over which we need to find the area is \([2, 3]\).
02
Set up the integral for the area
To find the area under the curve \(f(x) = x^3\) from \(x = 2\) to \(x = 3\), we need to evaluate the definite integral \(\int_{2}^{3} x^3 \, dx\).
03
Compute the integral
To find \(\int x^3 \, dx\), we use the power rule for integration. The integral of \(x^n\) is \(\frac{x^{n+1}}{n+1} + C\). Therefore, \(\int x^3 \, dx = \frac{x^4}{4} + C\).
04
Evaluate the indefinite integral using limits
Substitute the upper and lower limits into the evaluated indefinite integral: \(\left. \frac{x^4}{4} \right|_2^3 = \left( \frac{3^4}{4} \right) - \left( \frac{2^4}{4} \right)\).
05
Calculate the definite integral
Calculate \(\frac{3^4}{4} - \frac{2^4}{4}\). This simplifies to \(\frac{81}{4} - \frac{16}{4} = \frac{65}{4}\).
06
Conclusion
The area under the curve \(y = x^3\) from \(x=2\) to \(x=3\) is \(\frac{65}{4}\) square units.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Definite integral
A definite integral is a concept used to find the total area under a curve within a specific interval. This means calculating the area between the graph of a function and the x-axis, from one point to another. In our exercise, we explored the definite integral
- Function: \(f(x) = x^3\)
- Interval: [2, 3]
Power rule for integration
The power rule for integration is a nifty tool that helps simplify integrating power functions like those found in polynomial expressions. It is particularly useful for functions of the form \(x^n\). This rule states \[ \int x^n \, dx = \frac{x^{n+1}}{n+1} + C \]where \(C\) is the constant of integration, although for definite integrals, this constant eventually cancels out. Making use of the power rule in our example:
- Function: \(f(x)=x^3\)
Evaluating integrals
To convert an indefinite integral into a definite one, we substitute the upper and lower limits of the interval into the antiderivative. This effectively evaluates the integral. For our case:
- Upper Limit: \(x=3\)
- Lower Limit: \(x=2\)