Math Problem Statement

let f(x)=1-x^2. Find the difference quotient from x to h+h

Solution

Given the function f(x)=1x2f(x) = 1 - x^2, we want to find the difference quotient from xx to h+hh + h (which is essentially x+2hx + 2h).

The difference quotient is given by:

f(x+2h)f(x)(x+2h)x\frac{f(x+2h) - f(x)}{(x+2h) - x}

Step 1: Compute f(x+2h)f(x+2h)

Substitute x+2hx + 2h into f(x)f(x):

f(x+2h)=1(x+2h)2f(x + 2h) = 1 - (x + 2h)^2

Expanding (x+2h)2(x + 2h)^2:

(x+2h)2=x2+4xh+4h2(x + 2h)^2 = x^2 + 4xh + 4h^2

So,

f(x+2h)=1(x2+4xh+4h2)=1x24xh4h2f(x + 2h) = 1 - (x^2 + 4xh + 4h^2) = 1 - x^2 - 4xh - 4h^2

Step 2: Compute the difference f(x+2h)f(x)f(x+2h) - f(x)

Now subtract f(x)f(x) from f(x+2h)f(x+2h):

f(x+2h)f(x)=(1x24xh4h2)(1x2)f(x + 2h) - f(x) = (1 - x^2 - 4xh - 4h^2) - (1 - x^2)

Simplifying:

f(x+2h)f(x)=1x24xh4h21+x2f(x + 2h) - f(x) = 1 - x^2 - 4xh - 4h^2 - 1 + x^2

f(x+2h)f(x)=4xh4h2f(x + 2h) - f(x) = -4xh - 4h^2

Step 3: Divide by (x+2h)x=2h(x + 2h) - x = 2h

Now, compute the difference quotient:

f(x+2h)f(x)2h=4xh4h22h\frac{f(x+2h) - f(x)}{2h} = \frac{-4xh - 4h^2}{2h}

Simplifying:

4xh4h22h=2x2h\frac{-4xh - 4h^2}{2h} = -2x - 2h

Final Answer:

The difference quotient from xx to x+2hx + 2h is:

2x2h-2x - 2h

Would you like more details or have any questions?

Here are 5 related questions you can explore:

  1. What is the general form of the difference quotient for any function f(x)f(x)?
  2. How do you apply the difference quotient to polynomial functions?
  3. What happens to the difference quotient as h0h \to 0?
  4. How is the difference quotient related to the derivative of a function?
  5. Can you find the derivative of f(x)=1x2f(x) = 1 - x^2 using the difference quotient?

Tip: Always simplify algebraic expressions carefully before substituting them into the difference quotient to avoid mistakes.

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Math Problem Analysis

Mathematical Concepts

Algebra
Difference Quotient
Polynomial Functions

Formulas

Difference quotient formula: (f(x + h) - f(x)) / h
Quadratic expansion: (x + h)^2 = x^2 + 2xh + h^2

Theorems

Difference Quotient Theorem
Polynomial Expansion

Suitable Grade Level

Grades 10-12