The trapezium rule is defined as:[br][math]\int_a^bf(x)\mathrm{dx}\approx\frac{1}{2}h\left\{\left(y_0+y_n\right)+2\left(y_1+y_2+\ldots+y_{n-1}\right)\right\}[/math], where [math]h=\frac{b-a}{n}[/math].[br]This gives an [b]approximation [/b]to an integral, and is made more accurate by increasing [math]n[/math], the number of strips.[br][br]A common way of remembering the bit within { ... } is to treat it as [i]both of the ends and two times the middle values.[/i][i][br][/i]