Thread: Can someone help me with this problem

1. Can someone help me with this problem

(e^x/10 - x^2 - 1)dx {5
{-5

2. Originally Posted by 10164064
(e^x/10 - x^2 - 1)dx {5
{-5

$\int_{-5}^{5}e^{\frac{x}{10}}-x^2-1~~dx$

Well I will compute the antiderivative and you do the definite part

$\int{e^{\frac{x}{10}}~dx}=10\int{u}~du=10e^{\frac{ x}{10}}$

Now what substitution did I make?

$\int{x^2}~dx=\frac{x^3}{3}\longleftarrow\text{no surprises here}$

$\int~dx=x\longleftarrow\text{none here either}$

3. right i got that part but when I plug in the 5 and -5 I keep getting a negative answer when i subtract it

4. Originally Posted by 10164064
right i got that part but when I plug in the 5 and -5 I keep getting a negative answer when i subtract it

5. Ok thank you I just thought I was doing something wrong

6. Originally Posted by 10164064
Ok thank you I just thought I was doing something wrong
Well since

$\int_a^{b}f(x)~dx=F(b)-F(a)$ it is easily assumable that an integral can assume a negative value.

7. Originally Posted by 10164064
(e^x/10 - x^2 - 1)dx {5
{-5
Use brackets to make your meaning clear:

Something like:

integral [e^(x/10) - x^2 - 1] dx from -5 to 5

RonL