## What is double substitution?

The double substitution procedure is one in which a standard and an unknown weight of equal nominal value are compared twice to determine the average difference between the two weights. This procedure may be used for any nominal values provided adequate standards and equipment are available.

## What is the general formula for the substitution rule?

The substitution becomes very straightforward: ∫sinxcosx dx=∫u du=12u2+C=12sin2x+C. One would do well to ask “What would happen if we let u=cosx?” The result is just as easy to find, yet looks very different.

**What is the substitution rule for integrals?**

The substitution rule is a trick for evaluating integrals. It is based on the following identity between differentials (where u is a function of x): du = u dx . Most of the time the only problem in using this method of integra- tion is finding the right substitution. Example: Find ∫ cos 2x dx.

**Can you always use U substitution?**

5 Answers. 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.

### How do you know when to use 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.

### 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.

**When should you use u-substitution?**