Math Problem Statement

Expand (1 + 2x)^10 in ascending powers of x^4, up to and including the fourth term. Hence, evaluate (1.0002)^10 correct to four decimal places.

Solution

To solve this problem, let's break it down step-by-step.

Step 1: Expand (1+2x)10(1 + 2x)^{10} up to the fourth term in powers of xx.

This is a binomial expansion problem where we expand (1+2x)10(1 + 2x)^{10} using the Binomial Theorem: (1+2x)10=k=010(10k)(1)10k(2x)k(1 + 2x)^{10} = \sum_{k=0}^{10} \binom{10}{k} \cdot (1)^{10-k} \cdot (2x)^k

We are asked to expand up to and including the fourth term. So, we need the terms for k=0,1,2,3,k = 0, 1, 2, 3, and 44.

Terms Calculation:

  1. For k=0k = 0: (100)(1)10(2x)0=1\binom{10}{0} \cdot (1)^{10} \cdot (2x)^0 = 1

  2. For k=1k = 1: (101)(1)9(2x)1=102x=20x\binom{10}{1} \cdot (1)^{9} \cdot (2x)^1 = 10 \cdot 2x = 20x

  3. For k=2k = 2: (102)(1)8(2x)2=454x2=180x2\binom{10}{2} \cdot (1)^{8} \cdot (2x)^2 = 45 \cdot 4x^2 = 180x^2

  4. For k=3k = 3: (103)(1)7(2x)3=1208x3=960x3\binom{10}{3} \cdot (1)^{7} \cdot (2x)^3 = 120 \cdot 8x^3 = 960x^3

  5. For k=4k = 4: (104)(1)6(2x)4=21016x4=3360x4\binom{10}{4} \cdot (1)^{6} \cdot (2x)^4 = 210 \cdot 16x^4 = 3360x^4

Thus, the expansion of (1+2x)10(1 + 2x)^{10} up to the fourth term is: 1+20x+180x2+960x3+3360x41 + 20x + 180x^2 + 960x^3 + 3360x^4

Step 2: Use the expansion to evaluate (1.0002)10(1.0002)^{10}

To find (1.0002)10(1.0002)^{10}, we let x=0.0001x = 0.0001 in our expansion (1+2x)10(1 + 2x)^{10}.

Substitute x=0.0001x = 0.0001 into the expression: 1+20(0.0001)+180(0.0001)2+960(0.0001)3+3360(0.0001)41 + 20(0.0001) + 180(0.0001)^2 + 960(0.0001)^3 + 3360(0.0001)^4

Now, calculate each term:

  1. 20×0.0001=0.00220 \times 0.0001 = 0.002
  2. 180×(0.0001)2=180×0.00000001=0.0000018180 \times (0.0001)^2 = 180 \times 0.00000001 = 0.0000018
  3. 960×(0.0001)3=960×0.000000000001=0.000000096960 \times (0.0001)^3 = 960 \times 0.000000000001 = 0.000000096
  4. 3360×(0.0001)4=3360×0.0000000000000001=0.0000000003363360 \times (0.0001)^4 = 3360 \times 0.0000000000000001 = 0.000000000336

Add these terms together: 1+0.002+0.0000018+0.000000096+0.0000000003361.00200191 + 0.002 + 0.0000018 + 0.000000096 + 0.000000000336 \approx 1.0020019

Final Answer:

To four decimal places, (1.0002)101.0020(1.0002)^{10} \approx 1.0020.


Would you like a detailed explanation of any specific part? Here are some related questions that might expand your understanding:

  1. How does the Binomial Theorem work in general for any expansion (a+b)n(a + b)^n?
  2. What are binomial coefficients, and how are they calculated?
  3. Can the expansion be used for other values of nn or different terms in the series?
  4. What are some real-world applications of binomial expansion?
  5. Why do we approximate (1.0002)10(1.0002)^{10} using the first few terms only?

Tip: When dealing with binomial expansions for small changes (like 1.00021.0002), the first few terms usually provide a very close approximation.

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Math Problem Analysis

Mathematical Concepts

Binomial Expansion
Powers of a Binomial
Approximation

Formulas

Binomial Expansion: (a + b)^n = sum(k=0 to n) C(n, k) * a^(n-k) * b^k
C(n, k) = n! / (k!(n - k)!)

Theorems

Binomial Theorem

Suitable Grade Level

Grades 11-12