08 Binomial Theorem
Exercise 1
Question:
Using Binomial Theorem, indicate which number is large (1.1)^10000 or 1000.
Answer:
Answer:
- Using Binomial Theorem, we can expand (1.1)^10000 into a sum of terms as follows: (1.1)^10000 = ∑ (nCk) (1.1)^k (0.1)^(10000-k)
- Since 1000 is a constant, it does not change.
- Therefore, (1.1)^10000 is larger than 1000.
Question:
Using Binomial Theorem, evaluate (102)^5
Answer:
Answer: Step 1: The binomial theorem states that for any two numbers a and b, (a + b)^n = Σ (nCk)a^(n-k)b^k, where nCk is the combination of n things taken k at a time.
Step 2: Substitute a = 102 and b = 0 in the binomial theorem.
Step 3: Plug n = 5 into the equation.
Step 4: Calculate the value of (nCk)a^(n-k)b^k for k = 0, 1, 2, 3, 4, and 5.
Step 5: Add all the values of (nCk)a^(n-k)b^k together to get the result.
Answer: 10205025
Question:
Find (x+1)^6+(x−1)^6. Hence or otherwise evaluate (√2+1)^6+(√2−1)^6
Answer:
(x+1)^6+(x−1)^6
= (x^6 + 6x^5 + 15x^4 + 20x^3 + 15x^2 + 6x + 1) + (x^6 - 6x^5 + 15x^4 - 20x^3 + 15x^2 - 6x + 1)
= 2x^6 + 30x^4 + 30x^2 + 2
Now, substituting x = √2,
(√2+1)^6+(√2−1)^6
= 2(2)^6 + 30(2)^4 + 30(2)^2 + 2
= 128 + 480 + 120 + 2
= 630
Question:
Evaluate (96)^3
Answer:
Step 1: Multiply 96 by itself twice:
(96)^3 = 96 x 96 x 96
Step 2: Calculate 96 x 96:
(96)^3 = 96 x 96 x 96 = 9216 x 96
Step 3: Calculate 9216 x 96:
(96)^3 = 9216 x 96 = 8840192
Question:
Using Binomial Theorem, evaluate (101)^4
Answer:
Answer: Step 1: Using the Binomial Theorem, (a+b)^n = Σ(nCk)akbn-k, where n is the exponent and k is the index of summation.
Step 2: Substitute a = 101, b = 0, and n = 4 into the Binomial Theorem.
Step 3: Calculate the summation.
Step 4: (101)^4 = Σ(4Ck)101k0-k = Σ(4Ck)101k = 1 + 404 + 30,301 + 1,210,404.
Step 5: Therefore, (101)^4 = 1 + 404 + 30,301 + 1,210,404.
Question:
Expand the expression (2x−3)^6
Answer:
(2x−3)^6 = (2x)^6 − 6(2x)^5(3) + 15(2x)^4(3)^2 − 20(2x)^3(3)^3 + 15(2x)^2(3)^4 − 6(2x)(3)^5 + (3)^6
= 64x^6 - 1152x^53 + 5460x^43^2 - 8640x^33^3 + 5460x^23^4 - 1152x*3^5 + 3^6
Question:
Find (a+b)^4−(a−b)^4. Hence find s if (√3+√2)^4−(√3−√2)^4=40√s
Answer:
(a+b)^4−(a−b)^4 = a^4 + 4a^3b + 6a^2b^2 + 4ab^3 + b^4 - (a^4 - 4a^3b + 6a^2b^2 - 4ab^3 + b^4)
= 8a^3b + 24a^2b^2 + 16ab^3
Substituting a = √3 and b = √2,
(√3+√2)^4−(√3−√2)^4 = 8(√3)^3(√2) + 24(√3)^2(√2)^2 + 16(√3)(√2)^3
= 40√6
Hence, s = 6
Question:
Expand (x/3+1/x)^5
Answer:
Answer: Step 1: (x/3 + 1/x)^5 = Step 2: (x/3)^5 + 5(x/3)^4(1/x) + 10(x/3)^3(1/x)^2 + 10(x/3)^2(1/x)^3 + 5(x/3)(1/x)^4 + (1/x)^5 Step 3: x^5/243 + 5x^4/27 + 10x^3/9 + 10x^2/3 + 5x/x + 1/x^5 Step 4: x^5/243 + 5x^4/27 + 10x^3/9 + 10x^2/3 + 5 + 1/x^5
Question:
Expand (1−2x)^5
Answer:
(1−2x)^5 =
1 - 10x + 40x^2 - 80x^3 + 80x^4 - 32x^5
Question:
Expand (x+1/x)^6
Answer:
(x+1/x)^6 = (x^2 + 1)/x^2)^6 = (x^12 + 6x^10 + 15x^8 + 20x^6 + 15x^4 + 6x^2 + 1)/x^12 = x^0 + 6x^-2 + 15x^-4 + 20x^-6 + 15x^-8 + 6x^-10 + x^-12
Question:
Using Binomial theorem, evaluate (99)^5
Answer:
Answer: Step 1: Using Binomial theorem, (a+b)^n = (a^n) + (nC1)(a^(n-1)b) + (nC2)(a^(n-2)b^2) + …. + (nCn-1)(ab^(n-1)) + (b^n)
Step 2: Substitute a = 99 and b = 0 in the above equation.
Step 3: (99 + 0)^5 = (99^5) + (5C1)(99^40) + (5C2)(99^30^2) + (5C3)(99^20^3) + (5C4)(990^4) + (0^5)
Step 4: (99 + 0)^5 = (99^5) + (0) + (0) + (0) + (0) + (0)
Step 5: (99 + 0)^5 = (99^5)
Hence, the answer is 99^5 = 9,841,051,625.
Question:
Using binomial theorem, indicate which is larger (1.1)^10000 or 1000.
Answer:
- Using the binomial theorem, we can expand (1.1)^10000 as:
(1.1)^10000 = (1 + 0.1)^10000 =
1 + 10000(0.1) + (10000)(10000-1)/2 (0.1)^2 + … + (10000)(0.1)^10000
- Since the powers of 0.1 become increasingly small, we can ignore the terms after the first two and say that (1.1)^10000 is approximately equal to:
1 + 10000(0.1) = 1100
- Since 1100 is greater than 1000, (1.1)^10000 is larger than 1000.
Question:
Find (a+b)^4−(a−b)^4. Hence, evaluate (√3+√2)^4−(√3−√2)^4.
Answer:
Step 1: (a+b)^4−(a−b)^4 = (a^4 + 4a^3b + 6a^2b^2 + 4ab^3 + b^4) − (a^4 − 4a^3b + 6a^2b^2 − 4ab^3 + b^4)
Step 2: (a+b)^4−(a−b)^4 = 8a^3b + 16a^2b^2 + 8ab^3
Step 3: Substituting a = √3 and b = √2, we get
(√3+√2)^4−(√3−√2)^4 = 8(√3)(√2)^3 + 16(√3)^2(√2)^2 + 8(√3)^3(√2)
Step 4: Simplifying further, we get
(√3+√2)^4−(√3−√2)^4 = 24√6 + 32√12 + 24√3
Step 5: Hence, the required answer is
(√3+√2)^4−(√3−√2)^4 = 80√3
Question:
Show that 9^(n+1)−8n−9 is divisible by 64, whenever n is a positive integer
Answer:
- 9^(n+1) – 8n – 9
- 9^(n+1) – 8n – 9 = 9(9^n) – 8n – 9
- 9(9^n) – 8n – 9 = 9(9^n) – 8n – 9 + 8n
- 9(9^n) – 8n – 9 + 8n = 9(9^n) – 9 + 8n
- 9(9^n) – 9 + 8n = 9(9^n) – 9 + 8(8)
- 9(9^n) – 9 + 8(8) = 9(9^n) – 9 + 64
- 9(9^n) – 9 + 64 = 64(9^n - 1/8)
- 64(9^n - 1/8) is divisible by 64
Therefore, 9^(n+1)−8n−9 is divisible by 64, whenever n is a positive integer.
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