The first terms of the arithmetic progression are added. What is the sum?
Answer and explanation
Correct answer: A.
- Step 1: The tenth term is . Step 2. . Answer: 100. Why not the others: uses a wrong last term, forgets the division by , and is a sum for a different progression.
Practise more Mathematics A: Functions, Calculus, Complex Numbers and Probability.
Free questions with an explanation for every one, and full timed Exames Nacionais Secundário (Portugal) mock tests.