Integration by substitution

Integration by substitution is a way to do math when you're trying to figure out how much something is. It's like filling a cup with water. When you fill a cup with water, you are adding more water one cup at a time. Integration by substitution is the same idea--it's a way of adding numbers together to figure out the answer to a math question. The idea is to substitute one number for another, like replacing a cup of water with a bigger cup, to make the problem easier. So, for example, if you wanted to figure out how much water would fill an entire swimming pool, you could use integration by substitution. You'd start with a small cup and add it to a bigger cup to make the problem easier. You'd keep adding cups until you've added enough that it equals the size of the swimming pool.