Math Problem Statement

Find (f + g)(x), (f - g)(x), (f · g)(x), and (f/g)(x) for each f(x) and g(x). State the domain of each new function.

Solution

The problem asks to find four operations between functions f(x)f(x) and g(x)g(x) for each pair provided:

  • (f+g)(x)=f(x)+g(x)(f + g)(x) = f(x) + g(x)
  • (fg)(x)=f(x)g(x)(f - g)(x) = f(x) - g(x)
  • (fg)(x)=f(x)g(x)(f \cdot g)(x) = f(x) \cdot g(x)
  • (fg)(x)=f(x)g(x)\left(\frac{f}{g}\right)(x) = \frac{f(x)}{g(x)}

Additionally, you need to state the domain of each new function. The domain consists of all the xx-values for which the result is defined. Division by zero and square roots of negative numbers must be avoided in the domain.

Let’s walk through one example (the first one) and guide you in solving the rest.


Example 1:

f(x)=x2+4f(x) = x^2 + 4, g(x)=xg(x) = \sqrt{x}.

  1. Addition:
    (f+g)(x)=(x2+4)+x(f + g)(x) = (x^2 + 4) + \sqrt{x}
    Domain: x0x \geq 0, because x\sqrt{x} requires x0x \geq 0.

  2. Subtraction:
    (fg)(x)=(x2+4)x(f - g)(x) = (x^2 + 4) - \sqrt{x}
    Domain: x0x \geq 0, same reason as above.

  3. Multiplication:
    (fg)(x)=(x2+4)x(f \cdot g)(x) = (x^2 + 4) \cdot \sqrt{x}
    Domain: x0x \geq 0, since x\sqrt{x} must be defined.

  4. Division:
    (fg)(x)=x2+4x\left(\frac{f}{g}\right)(x) = \frac{x^2 + 4}{\sqrt{x}}
    Domain: x>0x > 0, because x\sqrt{x} cannot be zero.


You can follow a similar procedure for the other problems by applying these operations and checking for domains.

Would you like me to continue with the remaining problems or any specific one you find difficult?


5 Related Questions

  1. What happens to the domain when both functions contain square roots?
  2. How do you handle division by a function with multiple roots (like g(x)=x24g(x) = x^2 - 4)?
  3. What’s the domain if f(x)f(x) contains logarithms?
  4. How does the domain change for a quotient involving polynomial functions?
  5. How do you combine functions if both have restricted domains?

Tip: Always consider the individual domain restrictions from both f(x)f(x) and g(x)g(x) before combining. The final domain is their intersection!

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Math Problem Analysis

Mathematical Concepts

Function Operations
Domain of a Function
Algebraic Expressions
Square Roots and Polynomial Functions

Formulas

(f + g)(x) = f(x) + g(x)
(f - g)(x) = f(x) - g(x)
(f · g)(x) = f(x) · g(x)
(f / g)(x) = f(x) / g(x)

Theorems

Domain Restrictions
Division by Zero
Square Root of a Non-Negative Number

Suitable Grade Level

Grades 9-12