Aprēķins: yRWzvZ - 1
S_n =
| (a_1+a_n)* n |
| / 2 |
|
S_n =
$$S_{n}$$ = $$\frac{(a_{1}+a_{n})\cdot n}{2}$$
| (a_1+a_n)* n |
| / 2 |
S_n =
+
$$S_{n}$$ = $$\frac{a_{1}\cdot n}{2}+\frac{a_{n}\cdot n}{2}$$
| a_1* n |
| / 2 |
| a_n* n |
| / 2 |
S_n = 0.5* a_1* n+ 0.5* a_n* n$$S_{n}$$ = $$0.5\cdot a_{1}\cdot n+0.5\cdot a_{n}\cdot n$$