Topic Details (Notes format)

How to Use Summation Formulas for Arithmetic and Geometric Series

Subject: Mathematics

Book: Maths Mastery

Arithmetic series Sₙ= (n/2)(a₁+aₙ) or (n/2)[2a₁+(n–1)d] sums n terms. Geometric series Sₙ= a₁(1–rⁿ)/(1–r) for r≠1. These standard results handle repeated adding or multiplying patterns. For example, if an arithmetic sequence is 5, 8, 11,... with n=6 terms, sum is (6/2)[2×5+(6–1)×3]=3[10+15]=75. Mastery helps with finances (loan amortization), repeated additions in budgeting, or analyzing growth in discrete steps. Summation formulas are cornerstones of advanced math, bridging simple patterns to deep combinatorial or calculus expansions.

Practice Questions

If x + y = 10 and xy = 21, what is the value of x³ + y³?

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If 2x - 3 = 7, what is the value of x?

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If the sum of the angles of a polygon is 1080°, how many sides does the polygon have?

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If sin(A) = 3/5 and cos(B) = 5/13, where A and B are acute angles, what is sin(A+B)?

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If a cylinder has a radius of 7 cm and height of 10 cm, what is its volume?

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If a:b = 2:3 and b:c = 4:5, what is a:c?

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If the perimeter of a square is 40 cm, what is the area of the square?

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The sides of a triangle are 7, 24, and 25. Is this a right triangle?

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If a+b = 10 and ab = 21, what is the value of (a-b)^2?

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If x + 1/x = 5, what is the value of x^2 + 1/x^2?

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