Chapter 5: Problem 7
Evaluate the integral. \(\int_{-1}^{0}\left(2 x-e^{x}\right) d x\)
Short Answer
Expert verified
The definite integral evaluates to \(-2 + \frac{1}{e}\).
Step by step solution
01
Set Up the Integral
First, we need to evaluate the definite integral \(\int_{-1}^{0} (2x - e^x) \, dx\). This means we need to find the antiderivative of the function \(f(x) = 2x - e^x\) and then use the Fundamental Theorem of Calculus to calculate the definite integral from \(-1\) to \(0\).
02
Find the Antiderivative
To find the antiderivative of \(f(x) = 2x - e^x\), we integrate each term separately:- The antiderivative of \(2x\) is \(x^2\).- The antiderivative of \(-e^x\) is \(-e^x\).Therefore, the antiderivative \(F(x)\) of \(f(x)\) is \(F(x) = x^2 - e^x + C\), where \(C\) is the constant of integration.
03
Apply the Fundamental Theorem of Calculus
Now, we apply the Fundamental Theorem of Calculus, which tells us that: \[\int_{-1}^{0} (2x - e^x) \, dx = F(0) - F(-1)\]Substitute the values into the antiderivative:- \(F(0) = (0)^2 - e^{0} = -1\)- \(F(-1) = (-1)^2 - e^{-1} = 1 - \frac{1}{e}\) Thus, \[\int_{-1}^{0} (2x - e^x) \, dx = (-1) - \left(1 - \frac{1}{e}\right)\]
04
Simplify the Result
Simplify the expression:\[(-1) - \left(1 - \frac{1}{e}\right) = -1 - 1 + \frac{1}{e} = -2 + \frac{1}{e}\]Thus, the value of the integral is \(-2 + \frac{1}{e}\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Fundamental Theorem of Calculus
The Fundamental Theorem of Calculus is a cornerstone in understanding definite integrals. It bridges the world of differentiation and integration, providing a way to evaluate definite integrals through antiderivatives. In essence, the theorem consists of two main parts:
- The first part of the theorem tells us that if you have a continuous function and a point within its interval, you can express the accumulation function as an antiderivative.
- The second part lets us evaluate a definite integral by using antiderivatives. Specifically, if you have an antiderivative \( F(x) \) of \( f(x) \), then the definite integral from \( a \) to \( b \) is \( F(b) - F(a) \).
Antiderivatives
Antiderivatives are crucial when solving integrals, as they are essentially the reverse process of differentiation. To find an antiderivative, you look for a function whose derivative gives you the original function you started with. For example, the function \( f(x) = 2x \) has an antiderivative of \( x^2 \) because the derivative of \( x^2 \) is \( 2x \).
- The antiderivative of \( e^x \) is \( e^x \) itself since its derivative remains the same. Thus, the expression \( -e^x \) has an antiderivative of \( -e^x \).
- So overall, the antiderivative of \( 2x - e^x \) is \( x^2 - e^x \).
Exponential Functions
Exponential functions are unique mathematical expressions where the variable is in the exponent. The simplest exponential function is \( e^x \), where \( e \) is approximately equal to 2.71828, known as Euler's number. This type of function grows rapidly and is its own derivative:
- The differentiation or the derivative of \( e^x \) is \( e^x \), making it very special and powerful in calculus.
- Hence, its antiderivative is also \( e^x \).