The first term of an arithmetic progression is and the common difference is . Find the sum of the first terms.
Answer and explanation
Correct answer: C.
- Step 1: Use . Step 2. . **Answer: . Why not the others:** is what you get if you use in place of . is what you get if you forget to halve. is what you get if you put instead of in the formula.
Practise more Algebra, Analysis, Geometry and Stochastics.
Free questions with an explanation for every one, and full timed Maturität / Maturité (Switzerland) mock tests.