Rational Inequality using Binomial Theorem?
Consider the expression $(1 + x)^5$ and the inequality $0 < (1 + x)^5 < 100$. Use the binomial theorem to determine the range of values for $x$ that satisfy this inequality.
1 Answer
📌 CONCEPT: The binomial theorem allows us to expand expressions of the form (a + b)^n, where 'n' is a positive integer, and can be used to solve rational inequalities involving such expressions.
📐 RULE / FORMULA: According to the binomial theorem, the expansion of (a + b)^n is given by the formula: (a + b)^n = ∑[k=0 to n] (nCk) * (a^(n-k)) * (b^k), where nCk represents the binomial coefficient.
💡 WORKED EXAMPLE: To solve the inequality 0 < (1 + x)^5 < 100, we can use the binomial theorem to expand (1 + x)^5. The expansion will involve terms with increasing powers of x. By comparing the expanded expression to 100, we can determine the range of values for x that satisfy the inequality. The key is to identify the term with the highest power of x that does not exceed 100.
⚠️ COMMON MISTAKE: Students often forget to apply the binomial theorem correctly, or incorrectly expand the expression, leading to an incorrect solution. Additionally, they may not properly analyze the resulting inequality and identify the correct range of values for x.
16 Jun 26
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