# Integral of (x^2 + 1)^2

1. Jul 22, 2010

### Sidthewall

1. The problem statement, all variables and given/known data
How to find the integral of ((x^2) + 1)^2

My calc background.

I just started learning calc for the summer, so I making or missing little mistakes and i dont have an instructor to point it out to me. I see that some calc questions for me are easy such as the integral of x((x^2) + 1)^2,,, but for some strange reason I can't do ((x^2) + 1)^2.

3. The attempt at a solution
When I see this problem i couldn't find it anything to subsitute which is why i can't solve it, so I need a step by step way to solve this PLZ

2. Jul 22, 2010

### Gib Z

You don't need to substitute, just expand it.

3. Jul 22, 2010

### Sidthewall

K but the question said to use substitution

4. Jul 22, 2010

### Sidthewall

and what if i had ((x^2) + 1)^10, there must be a way to do it w/o expanding

5. Jul 22, 2010

### Gib Z

Okay, then use a Trig substitution. Think of the trig identities you know and decide which substitution would make it look like one of them. You can use the expansion for any powers of n, even large, whilst substitutions makes it very difficult for larger exponents.

6. Jul 22, 2010

### Sidthewall

K so I am thinking let u = (sinx)^2 + (sinx)^2 + (cosx)^2

7. Jul 22, 2010

### Gib Z

Try u=tan x.

8. Jul 22, 2010

????