Finding the Value of an Integral with U-Substitution

Here is one way to do it:Let u = x+1, then du = dx, and f(x+1) = f(u). Then$$\int_0^1 f(x+1)dx = \int_1^2 f(u)du = F(2) - F(1) = 7 - (-1) = 8$$So the answer is 8.In summary, using the given equations, we can use u-substitution to find the value of the integral 0∫1f(x+1)dx to be 8. This does not require knowing the equation of the function, just a simple substitution and using the given values.
  • #1
Zack K
166
6

Homework Statement


Suppose that: 02f(x)dx = 2 12f(x)dx = -1 and 24 = 7, find 01f(x+1)dx

Homework Equations


abf(x) = F(b) - F(a)

The Attempt at a Solution


So in these types of integration, we are needed to use u-substitution, the problem is, using u-substitution requires you to have the equation of the graph to get an exact value, but we just have f(x).I already evaluated 01f(x)dx = 3 if that helps at all.
 
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  • #2
Zack K said:

Homework Statement


Suppose that: 02f(x)dx = 2 12f(x)dx = -1 and 24 = 7, find 01f(x+1)dx

Homework Equations


abf(x) = F(b) - F(a)

The Attempt at a Solution


So in these types of integration, we are needed to use u-substitution, the problem is, using u-substitution requires you to have the equation of the graph to get an exact value, but we just have f(x).I already evaluated 01f(x)dx = 3 if that helps at all.

I don't understand your problem with a simple substitution. Why do you think you can't substitute here?
 
  • #3
Zack K said:

Homework Statement


Suppose that: 02f(x)dx = 2 12f(x)dx = -1 and 24 = 7, find 01f(x+1)dx
Without punctuation, he line above took me a while to figure out. At first I thought this meant ##\int_0^2 f(x)dx = 2 \cdot \int_1^2 f(x)dx = -1##. IOW that the values of the two integrals were -1 and -1/2, respectively.
Zack K said:

Homework Equations


abf(x) = F(b) - F(a)

The Attempt at a Solution


So in these types of integration, we are needed to use u-substitution, the problem is, using u-substitution requires you to have the equation of the graph to get an exact value, but we just have f(x).I already evaluated 01f(x)dx = 3 if that helps at all.
No, you don't need the equation of the function (f in this case). Just do a substitution and see what you get.
 

Related to Finding the Value of an Integral with U-Substitution

What is the formula for finding the area of f(x+1)?

The formula for finding the area of f(x+1) is the same as finding the area under a curve in calculus. It is given by the definite integral ∫f(x+1)dx, where f(x+1) is the function and dx represents the differential of x.

What does f(x+1) represent in the area formula?

f(x+1) represents the function that is being integrated to find the area under the curve. It is a mathematical representation of the relationship between the input variable x and the output variable f(x+1).

Can the area of f(x+1) be negative?

Yes, the area of f(x+1) can be negative if the function f(x+1) dips below the x-axis. This indicates that the function has negative values for certain inputs, resulting in a negative area under the curve.

How do you find the area of f(x+1) if the function is not given?

If the function f(x+1) is not given, you can still find the area by using the graphical interpretation of the definite integral. First, graph the function and then find the points where the function intersects the x-axis. Next, find the area of each individual shape formed by the x-axis and the function, and add them together to get the total area.

Can you use any method other than integration to find the area of f(x+1)?

No, the only way to find the area of f(x+1) is by using integration. This is because the area under a curve is defined by the definite integral, and there is no other mathematical method to accurately calculate this area.

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