Mathematics Grade 12 15 min

Pascal's triangle and the Binomial Theorem

Pascal's triangle and the Binomial Theorem

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1

Introduction & Learning Objectives

Learning Objectives Construct Pascal's triangle to any specified row and identify its key patterns. Relate the entries in Pascal's triangle to binomial coefficients, represented as C(n, k) or \(\binom{n}{k}\). State and apply the Binomial Theorem to expand binomials of the form (a + b)^n for any positive integer n. Calculate the coefficient of any specific term within a binomial expansion without performing the full expansion. Find the k-th term in the expansion of (a + b)^n using the general term formula. Solve problems involving binomial expansions, such as finding the constant term or the term with a specific power of a variable. How would you expand (x + y)⁸ without doing seven tedious multiplications? 🤔 There's a surprisingly elegant shortcut hidden in a...
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Key Concepts & Vocabulary

TermDefinitionExample BinomialA polynomial expression that contains exactly two terms.(2x - 5y), (a + b), or (x^2 + 1/x) Pascal's TriangleA triangular array of numbers in which the first and last number of each row is 1, and every other number is the sum of the two numbers directly above it.Row 4 is 1 4 6 4 1. The '6' is the sum of the '3' and '3' from the row above it. FactorialThe product of an integer and all the positive integers below it, denoted by an exclamation mark (!). By definition, 0! = 1.5! = 5 × 4 × 3 × 2 × 1 = 120 Binomial CoefficientThe coefficients of the terms in a binomial expansion. It is denoted by \(\binom{n}{k}\) or C(n, k), and represents the number of ways to choose k elements from a set of n elements.The coefficient of the x²y²...
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Core Formulas

The Binomial Theorem (a+b)^n = \sum_{k=0}^{n} \binom{n}{k} a^{n-k} b^k = \binom{n}{0}a^n b^0 + \binom{n}{1}a^{n-1}b^1 + ... + \binom{n}{n}a^0 b^n This is the fundamental formula for expanding any binomial raised to a positive integer power 'n'. It connects the expansion to the binomial coefficients. Binomial Coefficient Formula (Combinations) \binom{n}{k} = C(n,k) = \frac{n!}{k!(n-k)!} Use this formula to calculate any specific binomial coefficient without needing to construct Pascal's triangle. 'n' is the row number (starting from 0) and 'k' is the term position in that row (also starting from 0). General Term Formula T_{k+1} = \binom{n}{k} a^{n-k} b^k This formula allows you to find any specific term in the expansion without calcu...

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Sample Practice Questions

Challenging
If the constant term in the expansion of \(( \sqrt{x} - \frac{k}{x^2} )^{10}\) is 405, find the positive value of k.
A.9
B.3
C.5
D.81
Challenging
Find the coefficient of x⁵ in the expansion of \((x^2 - \frac{2}{x^3})^5\).
A.-10
B.10
C.-40
D.80
Challenging
The sum of the binomial coefficients in the expansion of (ax + by)ⁿ is 256. What is the value of n?
A.6
B.16
C.8
D.4

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