# Evaluate this integral

1. Jul 2, 2008

### jimen113

1. The problem statement, all variables and given/known data
$$\int$$$$^{5}_{0}$$ 1+2x$$^{3}$$

2. Relevant equations

3. The attempt at a solution
Integrating the function I get this: 1/2(x+x$$^{}4$$)
My answer when evaluating the limits =1/2(630)

2. Jul 2, 2008

### Hootenanny

Staff Emeritus
You might want to re-check your integral. What is:

$$\int 1 dx$$

3. Jul 2, 2008

### arildno

Why should an anti-derivative of 1 be 1/2x, rather than just x???

4. Jul 2, 2008

### jimen113

$$\int1$$=x
$$\int 2x^3$$ = $$\frac{x^4}{2}$$,
1/2$$\int$$x+x^4
I took (1/2) out of the $$\frac{X^{4}}{2}$$
(So, maybe I can't do that, I should leave it and evaluate at the limits using (x^4/2)?

5. Jul 2, 2008

### Hootenanny

Staff Emeritus
Note that:

$$x+\frac{1}{2}x^4 \neq \frac{1}{2}\left(x+x^4\right)$$

So yes, you need to evaluate:

$$\left.\left(x+\frac{1}{2}x^4\right)\right|_0^5$$

6. Jul 3, 2008

### jimen113

I see where I went wrong, thank you for your help!!