Integral of xex
The integral of xex is equal to xex - ex + C, where C is the constant of integration. Mathematically, we can write the formula for the integral of xe^x (OR xex) as ∫xex dx = xex - ex + C. This formula can be derived using the integration by parts method of integration. We can choose the first and second function using the sequence ILATE for applying the integration by parts formula and hence, determine the integral of xex.
Further, in this article, we will evaluate the integral of xe^x and find its formula using the integration by parts method. We will also determine the definite integral of xex with different limits and solve a few examples to evaluate the integral of functions including function xex for a better understanding of the concept.
1. | What is Integral of xex? |
2. | Integral of xe^x Formula |
3. | Integral of xex Proof |
4. | Definite Integral of xex |
5. | FAQs on Integral of xex |
What is Integral of xex?
The integral of xex (also, written as integral of xe^x) is equal to xex - ex + C. The integral of a function is nothing but the reverse process of differentiation. Therefore, the integral of xex is also called the antiderivative of xex. It can be calculated using one of the important methods of integration, known as the integration by parts method. The integral of a function gives the area under the curve of the function. So, we can say that the integral of xex gives the area under the curve of the function f(x) = xex. Let us go through the formula of the integral of xe^x in the next section:
Integral of xe^x Formula
The formula for the integration of xex is given by, ∫xex dx = xex - ex + C (OR) ∫xex dx = ex(x - 1) + C, where C is the integration constant, ∫ is the symbol of integration and dx shows the integral of xex is with respect to x. The image below shows the simplified formula of integral of xe^x and it can be evaluated using the ILATE method (also known as integration by parts method).
Integral of xex Proof
Now, we know that the formula for the integral of xex is given by, ∫xex dx = ex(x - 1) + C. We will derive this formula in this section using the integration by parts method (Product rule of integration). We will use the formula ∫f(x) g(x) dx = f(x) ∫g(x) dx - ∫[df/dx × ∫g(x) dx] dx. Here, we choose f(x) and g(x) according to ILATE - Inverse function, Logarithmic function, Algebraic function, Trigonometric function, and Exponential function. So, the first function f(x) = x (Because x is an algebraic function) and g(x) = ex (Because ex is an exponential function). We will also use the following formulas:
- Integral of e^x: ∫ex dx = ex + C
- Derivative of x: d(x)/dx = 1
Using the formulas, we have
∫xex dx = x ∫ex dx - ∫[dx/dx × ∫ex dx] dx
= xex - ∫(1 × ex) dx
= xex - ∫ex dx
= xex - ex + C
= ex (x - 1) + C
Hence, we have derived the formula for the integral of xex using the method of integration by parts.
Definite Integral of xex
In this section, we will evaluate the definite integral of xe^x with limits ranging from 0 to 1. We will substitute these limits into the formula of the integral of xex to find its definite integral. We know that ∫xex dx = ex(x - 1) + C, where C is the constant of integration. So, we have
0 ∫1 xex dx = [ ex(x - 1) + C ]01
= (e1(1 - 1) + C) - (e0(0 - 1) + C)
= (e × 0 + C) - (1 × -1 + C)
= C + 1 - C
= 1
Hence, the definite integral of xex from 0 to 1 is equal to 1.
Important Notes on Integral of xe^x
- The integral of xex is equal to ex(x - 1) + C, where C is the integration constant.
- We can calculate the integral of xe^x using the method of integration by parts.
- The definite integral of xex from 0 to 1 is equal to 1.
☛ Related Topics:
Integral of xex Examples
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Example 1: Find the integral of xe-x.
Solution: We will find the integral of xe-x in the same way as we calculated for the integral of xex. We will use the method of integration by parts and its formula given by, ∫f(x) g(x) dx = f(x) ∫g(x) dx - ∫[df/dx × ∫g(x) dx] dx. Here, f(x) = x and g(x) = e-x. We will also the formulas:
- dx/dx = 1
- ∫e-x dx = -e-x + C
Using these formulas, we have
∫xe-x dx = x ∫e-x dx - ∫[dx/dx × ∫e-x dx] dx
= -xe-x - ∫(1 × -e-x) dx
= -xe-x + ∫e-x dx
= -xe-x - e-x + C
= -e-x (x + 1) + C
Answer: ∫xe-x dx = -e-x (x + 1) + C, where C is the constant of integration.
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Example 2: Evaluate the integral of xe^(x^2), that is, xex2
Solution: To find the integral of xex2, we will use the substitution method of integration. Assume x2 = u, then differentiating both sides, we have 2x dx = du ⇒ xdx = du/2. Using this, we have
∫xex2 dx = ∫(eu/2) du
= (1/2) ∫eu du
= (1/2) eu + C --- [Because the integral of exponential function ex is equal to ex, that is, ∫ex dx = ex + C]
= (1/2) ex2 + C
Answer: Hence, the integral of e^x^2, that is, ∫xex2 dx is equal to (1/2) ex2 + C.
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Example 3: Calculate the integral of xex / (1 + x)2.
Solution: To calculate the integral of xex / (1 + x)2, we will use the method of integration by parts. We will use the formula ∫f(x) g(x) dx = f(x) ∫g(x) dx - ∫[df/dx × ∫g(x) dx] dx. We have
∫ [xex / (1 + x)2] dx = ∫[(x + 1 - 1) ex / (1 + x)2] dx
= ∫[(x + 1) ex / (1 + x)2 ] dx - ∫[ ex / (1 + x)2 ] dx
= ∫[ ex / (1 + x) ] dx - ∫[ ex / (1 + x)2 ] dx
Now, applying integration by parts formula, we have
= 1 / (1 + x) ∫ex dx - ∫[d(1 / (1 + x))/dx × ∫ex dx] dx - ∫[ ex / (1 + x)2 ] dx
= ex / (1 + x) - ∫[-1 / (1 + x)2 × ex ] dx - ∫[ ex / (1 + x)2 ] dx + C
= ex / (1 + x) + ∫[ ex / (1 + x)2 ] dx - ∫[ ex / (1 + x)2 ] dx + C
= ex / (1 + x) + C --- [Cancelling out ∫[ ex / (1 + x)2 ] dx]
Answer: Hence, integral of xex / (1 + x)2 is equal to ex / (1 + x) + C.
FAQs on Integral of xex
What is Integral of xex in Calculus?
The integral of xex is equal to xex - ex + C, where C is the constant of integration. The integral of xex gives the area under the curve of the function f(x) = xex. We can evaluate this integral using the integration by parts formula.
What is the Formula of Integral of xe^x?
The formula for the integration of xex is given by, ∫xex dx = xex - ex + C (OR) ∫xex dx = ex(x - 1) + C, where C is the integration constant. We can calculate this integral by using the ILATE sequence of function in integration by parts method.
How to Find the Integral of xex?
We can find the integral of xex using one of the most commonly used and important methods of integration known as the integration by parts. We can use the formula of integration by parts given by, ∫f(x) g(x) dx = f(x) ∫g(x) dx - ∫[df/dx × ∫g(x) dx] dx OR ∫udv = uv - ∫vdu.
What is the Definite Integral of xe^x From 0 to 1?
The definite integral of xe^x from 0 to 1 is equal to 1. This value can be determined by substituting the limits and 0 and 1 into the formula ∫xex dx = ex(x - 1) + C and find its value.
What is the Integral of x^e^x^2?
The integral of x^e^x^2 is given by, ∫xex2 dx = (1/2) ex2 + C. This formula of integral of x^e^(x^2) can be calculated using the substitution method of integration.
How Do You Find Integral of xex2?
We can find the integral of xex2 using the substitution method of integration. We can assume x2 to be equal to some variable u (say) and change the variable of integration to simplify the integral problem.
Is the Antiderivative of xex the Same as the Integral of xex?
Antidifferentiation is the reverse process of differentiation, which is also known as integration. Therefore, the antiderivative of xex is the same as the integral of xex. The antiderivative rules can be applied to find the integral of a function.
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