Math Problem Statement

Let 𝑓(π‘₯) = 5π‘₯2βˆ’1 π‘₯2 . Evaluate the function for the given values/expressions and simplify. a) f(3) = b) f(0) = c) f(-x) = d) f(1+x) =

Solution

We are given the function:

f(x)=5x2βˆ’1x2f(x) = \frac{5x^2 - 1}{x^2}

We will evaluate f(x)f(x) for each of the specified values.


a) f(3)f(3)

Substitute x=3x = 3 into the function:

f(3)=5(3)2βˆ’1(3)2=5(9)βˆ’19=45βˆ’19=449f(3) = \frac{5(3)^2 - 1}{(3)^2} = \frac{5(9) - 1}{9} = \frac{45 - 1}{9} = \frac{44}{9}

So, f(3)=449f(3) = \frac{44}{9}.


b) f(0)f(0)

Substitute x=0x = 0 into the function:

f(0)=5(0)2βˆ’1(0)2f(0) = \frac{5(0)^2 - 1}{(0)^2}

However, division by 0 is undefined. Thus, f(0)f(0) is undefined.


c) f(βˆ’x)f(-x)

Substitute x=βˆ’xx = -x into the function:

f(βˆ’x)=5(βˆ’x)2βˆ’1(βˆ’x)2f(-x) = \frac{5(-x)^2 - 1}{(-x)^2}

Since (βˆ’x)2=x2(-x)^2 = x^2:

f(βˆ’x)=5x2βˆ’1x2f(-x) = \frac{5x^2 - 1}{x^2}

So, f(βˆ’x)=f(x)=5x2βˆ’1x2f(-x) = f(x) = \frac{5x^2 - 1}{x^2}.


d) f(1+x)f(1+x)

Substitute x=1+xx = 1 + x into the function:

f(1+x)=5(1+x)2βˆ’1(1+x)2f(1+x) = \frac{5(1 + x)^2 - 1}{(1 + x)^2}

First, expand (1+x)2(1 + x)^2:

(1+x)2=1+2x+x2(1 + x)^2 = 1 + 2x + x^2

Now substitute this into the function:

f(1+x)=5(1+2x+x2)βˆ’11+2x+x2f(1+x) = \frac{5(1 + 2x + x^2) - 1}{1 + 2x + x^2}

Simplify the numerator:

5(1+2x+x2)βˆ’1=5+10x+5x2βˆ’1=4+10x+5x25(1 + 2x + x^2) - 1 = 5 + 10x + 5x^2 - 1 = 4 + 10x + 5x^2

Thus:

f(1+x)=4+10x+5x21+2x+x2f(1+x) = \frac{4 + 10x + 5x^2}{1 + 2x + x^2}


Let me know if you need more details or clarifications!

Expanding Understanding:

  1. What happens if f(x)f(x) is evaluated at any other negative number?
  2. How would the domain of f(x)f(x) change if it were defined as 5x2βˆ’1x\frac{5x^2 - 1}{x}?
  3. What is the symmetry of f(x)f(x)? Is it even, odd, or neither?
  4. How does the graph of f(x)f(x) behave as xβ†’βˆžx \to \infty?
  5. How would you find the derivative of f(x)f(x)?

Tip:

When simplifying fractions, always check for common factors in the numerator and denominator to reduce the expression fully.

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Math Problem Analysis

Mathematical Concepts

Rational Functions
Substitution
Simplification
Even and Odd Functions

Formulas

f(x) = \frac{5x^2 - 1}{x^2}

Theorems

Symmetry of functions (even/odd)
Undefined values in functions (division by zero)

Suitable Grade Level

Grades 10-12