- #1
Karol
- 1,380
- 22
Homework Statement
Homework Equations
$$1^2+2^2+3^2+...+n^2=\frac{n(n+1)(2n+1)}{6}$$
The Attempt at a Solution
$$S_n=2\{[f_1(x_1)-f_2(x_1)]\Delta x+[f_1(x_2)-f_2(x_2)]\Delta x+...+[f_1(x_{n-1})-f_2(x_{n-1})]\Delta x\}$$
$$S_n=2\{[18-\Delta x^2-\Delta x^2]+[18-(2\Delta x)^2-(2\Delta x)^2]+...+[18-(n-1)^2\Delta x^2-(n-1)^2\Delta x^2]\}$$
$$S_n=2\{\Delta x[(n-1)18-2(1^2+2^2+...+(n-1)^2)\Delta x]\}$$
If i develop exactly according to the formula in the Relevant Equations then it's wrong