# Integral evaluation.

1. Aug 9, 2005

### dx/dy=?

Question,
Evaluate:
$$\sum_{k=1}^{\ 6}\ f(xk)$$
where
$$\ xk\ = \ k/2$$
and
$$\ f(x)=sin\pi\ x$$

OK,
does this mean that that I should form a RiemannSum with;
$$sin\pi\ (k/2)* delt(k/2)= \sum_{k=1}^{\ 6}f(k/2)delt(k/2)$$

Im confused.

Last edited: Aug 9, 2005
2. Aug 9, 2005

### Maxos

I cannot see your problem, it is a trivial substitution

$$\sum_{k=1}^{\ 6}\ f(xk) = \sum_{k=1}^{\ 6}\ \sin(k\frac{\pi}{2})=1$$

3. Aug 10, 2005

### dx/dy=?

Thankyou,
sometimes I get muddled when working with calculus, and often percieve things as being a lot harder than they are.

Thanks again.

4. Aug 10, 2005

### Maxos

Ok, quite an usual occurrence!