09 Sequences and Series
Exercise 1
Question:
an=n(n^2+5)/4
Answer:
Step 1: Expand the expression to get ‘an = n^3 + 5n/4.’
Step 2: Multiply both sides of the equation by 4 to get ‘4an = 4n^3 + 20n.’
Step 3: Subtract 4n^3 from both sides of the equation to get ‘4an - 4n^3 = 20n.’
Step 4: Divide both sides of the equation by 4 to get ‘an = n^2 + 5/4.’
Question:
an=n(n−2)/(n+3);a20
Answer:
Step 1: Substitute n = 20 in the given equation. an=20(20−2)/(20+3);a20
Step 2: Simplify the equation. an=380/(23);a20
Step 3: Calculate the value of an. an = 16.5217;a20
Question:
an =n/(n+1)
Answer:
Step 1: Multiply both sides of the equation by (n + 1): an(n + 1) = n
Step 2: Isolate the n on the left side of the equation: an(n + 1) - n = 0
Step 3: Factor the left side of the equation: n(an + 1) = 0
Step 4: Set each factor equal to zero: n = 0 an + 1 = 0
Step 5: Solve each equation: n = 0 a = -1
Question:
an=n^2/2^n;a7
Answer:
a7 = (7^2)/2^7
a7 = (49)/128
a7 = 0.3828125
Question:
a1=3,an=3a(n−1)+2 for all n>1
Answer:
Step 1: Calculate a2: a2 = 3a(2−1)+2 a2 = 3a(1)+2 a2 = 3(3)+2 a2 = 11
Step 2: Calculate a3: a3 = 3a(3−1)+2 a3 = 3a(2)+2 a3 = 3(11)+2 a3 = 35
Question:
a1=−1,an=(an−1)/n,n≥2
Answer:
Step 1: a1 = -1
Step 2: a2 = (a1)/2 = (-1)/2 = -1/2
Step 3: a3 = (a2)/3 = (-1/2)/3 = -1/6
Step 4: a4 = (a3)/4 = (-1/6)/4 = -1/24
Step 5: a5 = (a4)/5 = (-1/24)/5 = -1/120
Step 6: a6 = (a5)/6 = (-1/120)/6 = -1/720
Step 7: a7 = (a6)/7 = (-1/720)/7 = -1/5040
Step 8: a8 = (a7)/8 = (-1/5040)/8 = -1/40320
Step 9: a9 = (a8)/9 = (-1/40320)/9 = -1/362880
Step 10: a10 = (a9)/10 = (-1/362880)/10 = -1/3628800
Question:
an=(−1)^(n−1)5(n+1)
Answer:
Step 1: Simplify the exponent: an = (-1)^(n-1)5(n+1)
Step 2: Rewrite the expression using the power rule: an = (-1) * 5 * (n^2 + n)
Question:
an=(−1)^(n−1)n^3;a9
Answer:
-
Replace ’n’ with ‘9’ in the equation: an=(−1)^(9−1)9^3
-
Simplify the equation: an=(−1)^8*9^3
-
Calculate the power of 9: an=(−1)^8*729
-
Calculate the power of -1: an=-1*729
-
Multiply the two numbers: an=-729
Question:
If a1=a2=2,an=a(n−1)−1(n>2) then a5 is ? A : 1 B : −1 C : 0’ D : −2
Answer:
Answer: B (-1) Step 1: a1=a2=2 Step 2: an=a(n−1)−1, for n>2 Step 3: a5=a4−1 Step 4: a4=a3−1 Step 5: a3=a2−1 Step 6: a2=2 Step 7: a3=1 Step 8: a4=0 Step 9: a5=−1
Question:
an=2^n
Answer:
- a1=2^1
- a2=2^2
- a3=2^3
- a4=2^4
- a5=2^5
- a6=2^6
- a7=2^7
- a8=2^8
- a9=2^9
- a10=2^10
Question:
an=4n−3;a17,a24
Answer:
a17 = 4(17) - 3 = 67
a24 = 4(24) - 3 = 95
title: “Exercise 1” parent: “09 Sequences and Series” draft: false
Question:
The fibonacci sequence is defined by a1=1=a2 ;
an=a(n−1)+a(n−2) for n>2.
Find (an+1)/an, for n=1,2,3,4,5.
A : 1,2,3/2 ,5/3 and 8/5
B : 1,2,3/2,4 and 8
C : 3,4,9/2, 5 and 8
D : 1,2,3/2, 6 and 9
Answer:
Answer: A
Question:
an=(2n−3)/6
Answer:
Step 1: Multiply both sides of the equation by 6.
6an = 2n - 3
Step 2: Add 3 to both sides of the equation.
6an + 3 = 2n
Step 3: Divide both sides of the equation by 2.
(6an + 3)/2 = n
JEE NCERT Solutions (Mathematics)
01 Sets
02 Relations and Functions
03 Trigonometric Functions
04 Principle of Mathematical Induction
05 Complex Numbers and Quadratic Equations
06 Linear Inequalities
07 Permutations and Combinations
08 Binomial Theorem
09 Sequences and Series
10 Straight Lines Exercise
10 Straight Lines Miscellaneous
11 Conic Sections
12 Introduction to Three Dimensional Geometry
13 Limits and Derivatives
14 Mathematical Reasoning
15 Statistics
16 Probability