9. Sequences and Series Mathematics Exercise - 9.1 class 11 Maths in English - CBSE Study
NCERT Solutions for Class 11 Mathematics are carefully prepared according to the latest CBSE syllabus and NCERT textbooks to help students understand every concept clearly. These solutions cover all important 9. Sequences and Series with detailed explanations and step-by-step answers for better exam preparation. Each Exercise 9.1 (Available) is explained in simple language so that students can easily grasp the fundamentals and improve their academic performance. The study material is designed to support daily homework, revision practice, and final exam preparation for Class 11 students. With accurate answers, concept clarity, and structured content, these NCERT solutions help learners build confidence and score higher marks in their examinations. Whether you are revising a specific topic or preparing an entire chapter, this resource provides reliable and syllabus-based guidance for complete success in Mathematics.
Class 11 English Medium Mathematics All Chapters:
9. Sequences and Series
1. Exercise 9.1 (Available)
Exercise 9.1
Write the first five terms of each of the sequences in Exercises 1 to 6 whose nth terms are:
Q1. Write the first five terms of the sequences whose nth term is an = n(n+2).
Solution: Q1.
is an = n(n+2)
Putting n = 1, 2, 3, 4 and 5 we obtain
a1 = 1(1 + 2) = 1× 3 = 3
a2 = 2(2 + 2) = 2× 4 = 8
a3 = 3(3 + 2) = 3× 5 = 15
a4 = 4(4 + 2) = 4× 6 = 24
a5 = 5(5 + 2) = 5× 7 = 35
Therefore, the five terms are 3, 8, 15, 24 and 35
Q5. Write the first five terms of the sequences whose nth term is an = (-1)n-15n+1
Solution: Q5.
an = (-1)n-15n+1
Putting n = 1, 2, 3, 4 and 5 we obtain
a1 = (-1)1-151+1 = (1)(5)2 = 25
a2 = (-1)2-152+1 = (-1) (5)3 = - 125
a3 = (-1)3-153+1 = (1) (5)4 = 625
a4 = (-1)4-154+1 = (-1) (5)5 = - 3125
a5 = (-1)5-155+1 = (1) (5)6 =156 25
Thus the five terms are 25, -125, 625, - 3125 and 15625
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