## How do you use substitution method in integration?

According to the substitution method, a given integral ∫ f(x) dx can be transformed into another form by changing the independent variable x to t. This is done by substituting x = g (t). Now, substitute x = g(t) so that, dx/dt = g'(t) or dx = g'(t)dt.

### How do you know when to use u-substitution?

- u-sub, undoes the chain rule. The chain rule always leaves a derivative of “an inside” function multiplied at the end.
- Use u-sub when you can factor/manipulate the integrand into multiplication AND you see an inside function who’s derivative is nearby.
- Integration by parts is used to undo the product rule.

#### Why do we use u-substitution?

𝘶-Substitution essentially reverses the chain rule for derivatives. In other words, it helps us integrate composite functions. When finding antiderivatives, we are basically performing “reverse differentiation.” Some cases are pretty straightforward.

**When can you use U-substitution?**

u-sub, undoes the chain rule. The chain rule always leaves a derivative of “an inside” function multiplied at the end. Use u-sub when you can factor/manipulate the integrand into multiplication AND you see an inside function who’s derivative is nearby. Integration by parts is used to undo the product rule.

**What is the difference between U-substitution and integration by parts?**

Integration by parts is for functions that can be written as the product of another function and a third function’s derivative. A good rule of thumb to follow would be to try u-substitution first, and then if you cannot reformulate your function into the correct form, try integration by parts.

## What does Du DX mean?

du and dx are just parts of a derivative, where of course u is substituted part fo the function. u will always be some function of x, so you take the derivative of u with respect to x, or in other words du/dx.

### How do you know if you need to use u-substitution?

Always do a u-sub if you can; if you cannot, consider integration by parts. A u-sub can be done whenever you have something containing a function (we’ll call this g), and that something is multiplied by the derivative of g.

#### What is the purpose of u-substitution?

U-substitution is a method used to turn harder to solve integrals into a more recognizable one. Let’s look at and example to see. ∫2x(x2+4)100dx Now you could simplify out the expression to the hundredth power and then take the integral of each individual part but I certainly don’t want to do that.

**What is du equal to in differential form?**

We know that du– if we want to write it in differential form– du is equal to 7 times dx. So du is equal to 7 times dx. That part right over there is equal to du. And if we want to care about u, well, that’s just going to be the 7x plus 9.

**What is du equal to 7 times DX?**

We know that du– if we want to write it in differential form– du is equal to 7 times dx. So du is equal to 7 times dx. That part right over there is equal to du. And if we want to care about u, well, that’s just going to be the 7x plus 9. That is are u. So let’s rewrite this indefinite integral in terms of u.

## When to use-substitution in calculus?

We need to use -substitution. Imagine you’re trying to find . You might say “since is the derivative of , we can use -substitution.” Actually, since -substitution requires taking the derivative of the inner function, must be the derivative of for -substitution to work.

### Why can’t I use-substitution with the derivative of a function?

You might say “since is the derivative of , we can use -substitution.” Actually, since -substitution requires taking the derivative of the inner function, must be the derivative of for -substitution to work. Since that’s not the case, -substitution doesn’t apply here.