Math Problem Statement

Given f(x) = 2x^2 + 7x - 15 and g(x) = 3 - 2x, what is f(x)/g(x) for all defined values? The options are: (1) -x - 5 (2) -x + 5 (3) x - 5 (4) x + 5

Solution

Let's solve the problem step by step:

We are given:

  • f(x)=2x2+7x15f(x) = 2x^2 + 7x - 15
  • g(x)=32xg(x) = 3 - 2x

We need to calculate f(x)g(x)\frac{f(x)}{g(x)} for all defined values.

Step 1: Factor f(x)f(x)

The quadratic f(x)=2x2+7x15f(x) = 2x^2 + 7x - 15 needs to be factored. To factor this, find two numbers that multiply to 2×(15)=302 \times (-15) = -30 and add to 77. These numbers are 1010 and 3-3.

Now split the middle term: f(x)=2x2+10x3x15f(x) = 2x^2 + 10x - 3x - 15 Group terms: f(x)=(2x2+10x)(3x+15)f(x) = (2x^2 + 10x) - (3x + 15) Factorize each group: f(x)=2x(x+5)3(x+5)f(x) = 2x(x + 5) - 3(x + 5) Factor out (x+5)(x + 5): f(x)=(2x3)(x+5)f(x) = (2x - 3)(x + 5)

Step 2: Write f(x)g(x)\frac{f(x)}{g(x)}

Substitute the factored form of f(x)f(x): f(x)g(x)=(2x3)(x+5)32x\frac{f(x)}{g(x)} = \frac{(2x - 3)(x + 5)}{3 - 2x}

Step 3: Simplify g(x)=32xg(x) = 3 - 2x

Notice that g(x)=32x=(2x3)g(x) = 3 - 2x = -(2x - 3). Substitute this into the fraction: f(x)g(x)=(2x3)(x+5)(2x3)\frac{f(x)}{g(x)} = \frac{(2x - 3)(x + 5)}{-(2x - 3)}

Cancel 2x32x - 3, as long as 2x302x - 3 \neq 0: f(x)g(x)=(x+5)\frac{f(x)}{g(x)} = -(x + 5)

Final Answer:

f(x)g(x)=x5\frac{f(x)}{g(x)} = -x - 5 This corresponds to option (1).


Would you like a more detailed explanation of any step? Here are 5 related questions for practice:

  1. How do you factorize a quadratic equation effectively?
  2. What happens if g(x)=0g(x) = 0? Why do we exclude these values?
  3. How do you simplify a rational expression like f(x)g(x)\frac{f(x)}{g(x)}?
  4. Why is it important to rewrite g(x)=32xg(x) = 3 - 2x as (2x3)-(2x - 3)?
  5. What is the domain of f(x)g(x)\frac{f(x)}{g(x)}, and how is it determined?

Tip: Always check for restrictions in the denominator before canceling terms in a fraction!

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Math Problem Analysis

Mathematical Concepts

Polynomial Division
Factoring Quadratic Equations
Simplifying Rational Expressions

Formulas

Factoring quadratic equations: ax^2 + bx + c = 0
Simplification: Cancel common factors in rational expressions

Theorems

Zero Product Property
Restrictions on Rational Expressions (denominator ≠ 0)

Suitable Grade Level

Grades 10-12