Math Problem Statement

If rational expression (x^2 - 5x - 3) / (3x^2 + 14x + 5) ÷ (4x - 12) / (x + 5) is reciprocated, it will be: (x^2 - 5x - 3) / (3x^2 + 14x + 5) × (x + 5) / (4x - 12). What is the factored form?

Solution

Let's analyze and solve this problem.

Problem Breakdown:

We are given a rational expression:
x25x33x2+14x+5÷4x12x+5\frac{x^2 - 5x - 3}{3x^2 + 14x + 5} \div \frac{4x - 12}{x + 5} This is then reciprocated and simplified. The task is to find the factored form.


Step 1: Rewrite the division as multiplication

Division of fractions means multiplying by the reciprocal of the second fraction: x25x33x2+14x+5÷4x12x+5=x25x33x2+14x+5×x+54x12\frac{x^2 - 5x - 3}{3x^2 + 14x + 5} \div \frac{4x - 12}{x + 5} = \frac{x^2 - 5x - 3}{3x^2 + 14x + 5} \times \frac{x + 5}{4x - 12}


Step 2: Factorize all components

  1. Numerator of the first fraction: x25x3x^2 - 5x - 3
    This cannot be factored further (no simple roots). It remains as it is.

  2. Denominator of the first fraction: 3x2+14x+53x^2 + 14x + 5
    Factorizing this quadratic:

    • Multiply 3×5=153 \times 5 = 15
    • Find two numbers that multiply to 15 and add to 14: 1515 and 11
    • Split the middle term:
      3x2+15x+x+5=(3x2+15x)+(x+5)=3x(x+5)+1(x+5)=(3x+1)(x+5)3x^2 + 15x + x + 5 = (3x^2 + 15x) + (x + 5) = 3x(x + 5) + 1(x + 5) = (3x + 1)(x + 5) So, 3x2+14x+5=(3x+1)(x+5)3x^2 + 14x + 5 = (3x + 1)(x + 5).
  3. Numerator of the second fraction: x+5x + 5
    This is already factored.

  4. Denominator of the second fraction: 4x124x - 12
    Factor out 4:
    4x12=4(x3)4x - 12 = 4(x - 3)


Step 3: Rewrite the expression

Substituting the factored components: x25x3(3x+1)(x+5)×x+54(x3)\frac{x^2 - 5x - 3}{(3x + 1)(x + 5)} \times \frac{x + 5}{4(x - 3)}


Step 4: Cancel common terms

The x+5x + 5 terms in the numerator and denominator cancel out. The simplified expression becomes: x25x3(3x+1)×14(x3)=x25x34(3x+1)(x3)\frac{x^2 - 5x - 3}{(3x + 1)} \times \frac{1}{4(x - 3)} = \frac{x^2 - 5x - 3}{4(3x + 1)(x - 3)}


Step 5: Match the options

Now, let's rewrite this to match the given answer choices. The numerator x25x3x^2 - 5x - 3 remains unfactored. The denominator is 4(3x+1)(x3)4(3x + 1)(x - 3).

The correct choice is: [ \boxed{d. \frac{2x + 1}{3x - 1}} \Let me know if you want details about additional factoring concepts or step-by-step verification?

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Math Problem Analysis

Mathematical Concepts

Rational Expressions
Factoring Quadratics
Simplifying Rational Expressions

Formulas

Division of fractions: a/b ÷ c/d = a/b × d/c
Factoring quadratic equations: ax^2 + bx + c = (px + q)(rx + s)

Theorems

Fundamental Theorem of Algebra
Factoring Quadratics

Suitable Grade Level

Grade 9-10