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a. Use the Quotient Rule to find the derivative of the given function. Simplify your result. b. Find the derivative by first simplifying the function. Verify that your answer agrees with part \((a)\) \(y=\frac{x^{2}-a^{2}}{x-a},\) where \(a\) is a constant.

Short Answer

Expert verified
Answer: Yes, the derivatives found in part (a) and part (b) agree.

Step by step solution

01

Part (a): Find the derivative using the Quotient Rule

To find the derivative of the function \(y=\frac{x^{2}-a^{2}}{x-a}\) using the Quotient Rule, use the formula: $$\frac{d}{dx}\left(\frac{u}{v}\right) = \frac{vu'(x) - u(x)v'(x)}{(v(x))^2}$$ Here, \(u(x) = x^{2} - a^{2}\) and \(v(x) = x - a\). Let's find their derivatives. First, find the derivative of \(u(x)\): $$u'(x) = \frac{d}{dx}(x^{2}-a^{2}) = 2x$$ Then, find the derivative of \(v(x)\): $$v'(x) = \frac{d}{dx}(x-a) = 1$$ Now, plug in \(u(x)\), \(u'(x)\), \(v(x)\), and \(v'(x)\) into the Quotient Rule: $$\frac{d}{dx}\left(\frac{x^{2}-a^{2}}{x-a}\right) = \frac{(x - a)(2x) - (x^{2} - a^{2})(1)}{(x-a)^2}$$
02

Part (a): Simplify the result

Now, simplify the expression: $$\frac{(2x^{2} - 2ax) - (x^{2} - a^{2})}{(x-a)^2} = \frac{x^2 - 2ax + a^{2}}{(x-a)^2}$$ This is the simplified derivative of the function using the Quotient Rule.
03

Part (b): Simplify the function first

Before finding the derivative of the given function, we need to simplify it. $$y=\frac{x^{2}-a^{2}}{x-a}$$ Notice that the numerator is a difference of squares. We can factor it: $$y = \frac{(x-a)(x+a)}{x-a}$$ Now, simplify by canceling the \((x - a)\) terms: $$y = x + a$$
04

Part (b): Find the derivative

Now, find the derivative of the simplified function: $$\frac{d}{dx}(x+a) = 1$$ This is the derivative of the simplified function.
05

Verify the answers

We found the derivative of the function using both the Quotient Rule and by simplifying the function first. The derivatives should be equivalent: $$\frac{x^2 - 2ax + a^{2}}{(x-a)^2} = 1$$ To further simplify and verify, multiply both sides of the equation by \((x-a)^2\): $$x^2 - 2ax + a^{2} = (x-a)^2$$ Expand the right side: $$x^2 - 2ax + a^{2} = x^2 - 2ax + a^{2}$$ Both sides are equal, so the derivatives found in part (a) and part (b) agree.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Quotient Rule
When dealing with the derivatives of functions presented as fractions, the Quotient Rule is an essential tool in calculus. This rule tells us how to differentiate functions where one function is divided by another. The rule is expressed through the equation:
  • \( \frac{d}{dx}\left(\frac{u}{v}\right) = \frac{vu'(x) - u(x)v'(x)}{(v(x))^2} \)
Here, \(u(x)\) is the numerator and \(v(x)\) is the denominator. The derivatives of these functions, \(u'(x)\) and \(v'(x)\), are required to form the expression.
In our example, we applied the Quotient Rule to the function \( y = \frac{x^2-a^2}{x-a} \). We identified \( u(x) = x^2 - a^2 \) and \( v(x) = x-a \), and calculated their derivatives as:\( u'(x) = 2x \) and \( v'(x) = 1 \).
After substituting these derivatives back into the Quotient Rule, we can find the derivative of the function in terms of both the original functions and their derivatives.
Simplification
In calculus, simplifying expressions before finding derivatives can often make the process easier. Simplification involves reducing the complexity of an expression without changing its value.
For the given function, \( y = \frac{x^2-a^2}{x-a} \), simplification involves recognizing it as a difference of squares. This means the numerator can be factored into \( (x-a)(x+a) \).
Simplifying it further by canceling out the common term \( (x-a) \) from the numerator and denominator gives us:
  • \( y = x + a \)
Now the function is much simpler to differentiate. This simplified form reveals some hidden capabilities to compute the derivative that may not be directly obvious in its complex form.
Difference of Squares
The difference of squares is a mathematical principle where you can rewrite expressions of the form \( A^2 - B^2 \) as \((A+B)(A-B)\).
In our exercise, \(x^2-a^2\) is a difference of squares. Recognizing this helps in breaking down the expression for simplification. Factoring \(x^2-a^2\) into \((x-a)(x+a)\) dramatically simplifies the derivative finding process.
In mathematics, expressions that can be reduced using the difference of squares often lead to simpler calculations, removing the need for more complex operations.
Verification of Derivatives
Verification is a key part of solving calculus problems, ensuring that different methods of obtaining derivatives result in the same, correct solution.
Initially, the derivative of \( y = \frac{x^2-a^2}{x-a} \) was found using the Quotient Rule, giving us a more complicated expression.
  • Quotient Rule Derivative: \( \frac{x^2 - 2ax + a^2}{(x-a)^2} \)
After simplifying the function to \( y = x + a \) and finding its derivative, which is 1, both results were placed side by side to ensure their equivalence.
This process involves showing that multiplying the simplified denominator across brings both forms to the same expression. This step confirms the correctness of our derivative calculations from both approaches.

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