Civil Service Exam (Subprofessional) Numerical Ability — Algebra, Exponents & Number SeriesFlash Cards

What is the Product Rule for exponents and how do you apply it?

The Product Rule states that when multiplying two exponents with the same base, you keep the base and add the powers: a^m × a^n = a^(m+n). Example: 5^3 × 5^2 = 5^(3+2) = 5^5. This rule works for any real numbers m and n, including negative exponents.

Quotient Rule

The Quotient Rule for exponents: When dividing two exponents with the same base, keep the base and subtract the powers: a^m ÷ a^n = a^(m-n). Example: 10^5 ÷ 10^3 = 10^(5-3) = 10^2 = 100. This helps avoid negative exponents by putting the answer in the appropriate position.

What happens when you raise a power to another power?

Use the Power Rule: (a^m)^n = a^(mn). Multiply the exponents together. Example: (2^3)^4 = 2^(3×4) = 2^12 = 4,096. Another example: Express 8^3 as a power with base 2: Since 8 = 2^3, then 8^3 = (2^3)^3 = 2^9.

Zero-Exponent Rule

Any non-zero number raised to the power of zero equals 1: a^0 = 1 (where a ≠ 0). Examples: 5^0 = 1, (-3)^0 = 1, (999)^0 = 1. This rule is fundamental for simplifying expressions and solving equations.

How do you handle negative exponents?

Negative Exponent Rule: a^(-m) = 1/a^m. A negative exponent means take the reciprocal and make the exponent positive. Example: 2^(-2) = 1/2^2 = 1/4. For fractions: (3/4)^(-2) = (4/3)^2 = 16/9.

Fractional Exponent Rule

Fractional exponents represent roots: a^(1/n) = ⁿ√a. The denominator of the fraction becomes the index of the root. Example: 4^(1/2) = √4 = 2, 8^(1/3) = ∛8 = 2. For a^(m/n) = ⁿ√(a^m) or (ⁿ√a)^m.

What are the 6 steps for simplifying exponential expressions?

1. Apply Product Rule (add exponents with same base) 2. Apply Quotient Rule (subtract exponents) 3. Apply Power Rule (multiply exponents) 4. Apply Zero-Exponent Rule (anything^0 = 1) 5. Apply Negative Exponent Rule (move to opposite position) 6. Simplify coefficients and reduce fractions

Arithmetic Sequence

A sequence where the difference between consecutive terms is constant. Formula for nth term: aₙ = a₁ + (n-1)d, where a₁ is the first term, d is the common difference, and n is the term number. Example: 2, 5, 8, 11, 14... has d = 3.

How do you identify and continue a geometric sequence?

Geometric Sequence: Each term is obtained by multiplying the previous term by a constant ratio (r). Formula: aₙ = a₁ × r^(n-1). Example: 3, 6, 12, 24, 48... has r = 2. To find the next term, multiply the last term by the common ratio: 48 × 2 = 96.

What characterizes a Fibonacci sequence?

Fibonacci Sequence: Each term is the sum of the two preceding terms. Pattern: aₙ = aₙ₋₁ + aₙ₋₂. Example: 1, 1, 2, 3, 5, 8, 13, 21... where 1+1=2, 1+2=3, 2+3=5, etc. This pattern appears frequently in nature and mathematics.

Solve: 8x⁵/4x² = ?

Apply the quotient rule and simplify coefficients: 8x⁵/4x² = (8/4) × (x⁵/x²) = 2 × x⁵⁻² = 2x³ Always separate coefficients from variables and apply exponent rules to each part.

What is an exponent sequence and how do you recognize it?

Exponent Sequence: All terms are perfect powers (squares, cubes, etc.). Two types: 1. Perfect squares: 4, 9, 16, 25, 36, 49... (2², 3², 4², 5², 6², 7²...) 2. Perfect cubes: 8, 64, 216, 512, 1000... (2³, 4³, 6³, 8³, 10³...) Look for patterns in the base numbers or exponents.

Compare arithmetic and geometric sequences

Arithmetic Sequence: - Constant difference between terms - Linear growth pattern - Formula: aₙ = a₁ + (n-1)d - Example: 5, 8, 11, 14... Geometric Sequence: - Constant ratio between terms - Exponential growth/decay - Formula: aₙ = a₁ × r^(n-1) - Example: 5, 10, 20, 40...

In the sequence 3, 8, 15, 24, 35, ?, what's the pattern and next term?

This is an alternating sequence. Find the differences: 8-3=5, 15-8=7, 24-15=9, 35-24=11 The differences form: 5, 7, 9, 11... (increasing by 2 each time) Next difference: 11+2=13 Next term: 35+13=48

What is a mixed sequence in number series?

Mixed Sequence: Uses multiple arithmetic operations in a pattern. Example: 10, 22, 46, 94, 190, ? Pattern: multiply by 2, then add 2 10×2+2=22, 22×2+2=46, 46×2+2=94, 94×2+2=190, 190×2+2=382 These sequences require identifying the combination of operations used.

Simplify: (3x²y⁻²)(4xy³)

Multiply coefficients and apply product rule for exponents: (3x²y⁻²)(4xy³) = (3×4)(x²×x¹)(y⁻²×y³) = 12x²⁺¹y⁻²⁺³ = 12x³y¹ = 12x³y Remember: when multiplying with same base, add the exponents.

What is a two-stage sequence?

Two-Stage Sequence: The differences between consecutive terms form their own pattern (arithmetic or geometric). Example: 1, 3, 5, 9, 11 - missing terms can be found by analyzing that differences should be 2, 2, 4, 2, following a pattern. First find the pattern in differences, then fill in missing terms.

Evaluate: 2⁻³ × 2⁵ ÷ 2¹

Apply exponent rules step by step: 2⁻³ × 2⁵ ÷ 2¹ = 2⁻³⁺⁵⁻¹ = 2¹ = 2 Alternatively: 2⁻³ × 2⁵ = 2² = 4, then 4 ÷ 2¹ = 4 ÷ 2 = 2 Both methods give the same answer.

Combination Sequence

Combination Sequence: Uses elements from different sequence types (like alternating between operations). Example: 3, 3, 3, 6, 3, 9, 3, 12... Pattern: Odd positions stay constant (3), even positions increase by 3 (3, 6, 9, 12...) This combines constant and arithmetic patterns.

What are the key strategies for solving number series problems?

1. Look for constant differences (arithmetic) 2. Check for constant ratios (geometric) 3. Examine if terms are perfect powers 4. Try sum patterns (Fibonacci-type) 5. Look for alternating patterns 6. Check differences between differences 7. Consider mixed operations 8. Identify if it's a combination sequence Always verify your pattern with given terms before finding the answer.