Math Problem Statement

The difference quotation for f(x)= -1/x at the point [-4, 1/4] is ?

Solution

To find the difference quotient of f(x)=1xf(x) = -\frac{1}{x} at the point (4,14)(-4, \frac{1}{4}), we use the definition of the difference quotient:

f(x+h)f(x)h\frac{f(x + h) - f(x)}{h}

Here, we are specifically interested in the point (4,14)(-4, \frac{1}{4}). Thus, we set x=4x = -4.

The difference quotient at x=4x = -4 is:

f(4+h)f(4)h\frac{f(-4 + h) - f(-4)}{h}

Now we compute f(4)f(-4) and f(4+h)f(-4 + h):

f(4)=14=14f(-4) = -\frac{1}{-4} = \frac{1}{4}

f(4+h)=14+hf(-4 + h) = -\frac{1}{-4 + h}

Substituting these into the difference quotient formula:

f(4+h)f(4)h=14+h14h\frac{f(-4 + h) - f(-4)}{h} = \frac{-\frac{1}{-4 + h} - \frac{1}{4}}{h}

To simplify, we find a common denominator for the fractions in the numerator:

14+h14=4+(4+h)4(4+h)=4(4h)4(4+h)=h4(4+h)-\frac{1}{-4 + h} - \frac{1}{4} = -\frac{4 + (-4 + h)}{4(-4 + h)} = -\frac{4 - (4 - h)}{4(-4 + h)} = -\frac{h}{4(-4 + h)}

Substitute this back into the difference quotient:

h4(4+h)h=hh4(4+h)=14(4+h)\frac{-\frac{h}{4(-4 + h)}}{h} = -\frac{h}{h \cdot 4(-4 + h)} = -\frac{1}{4(-4 + h)}

Therefore, the difference quotient for f(x)=1xf(x) = -\frac{1}{x} at the point (4,14)(-4, \frac{1}{4}) is:

f(4+h)f(4)h=14(4+h)\frac{f(-4 + h) - f(-4)}{h} = -\frac{1}{4(-4 + h)}

Would you like further details or have any other questions?

Here are 5 numbered questions you might ask next:

  1. How do you compute the derivative of a function at a point using limits?
  2. Can you explain the difference between a difference quotient and a derivative?
  3. How do you handle difference quotients for more complex functions?
  4. Can you provide an example of finding the difference quotient for a polynomial function?
  5. What are some common applications of difference quotients in calculus?

Tip: Practice simplifying complex fractions and finding common denominators to become more comfortable with difference quotient problems.

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Math Problem Analysis

Mathematical Concepts

Calculus
Difference Quotient

Formulas

Difference quotient formula

Theorems

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Suitable Grade Level

Advanced High School