Problem

Find dy/dx y(x^2+16)=32

The given problem is asking for the derivative of the function with respect to x, symbolized as dy/dx. The function in question has the form y multiplied by a quantity involving x, which in this case is x^2+16, and this product is equal to a constant value, 32. To find dy/dx, you will need to differentiate both sides of the equation with respect to x, applying the appropriate rules for differentiation such as the product rule, the chain rule, and/or the constant multiple rule as necessary.

$y \left(\right. x^{2} + 16 \left.\right) = 32$

Answer

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Solution:

Step 1:

Take the derivative of both sides with respect to $x$: $\frac{d}{dx}(y(x^2 + 16)) = \frac{d}{dx}(32)$.

Step 2:

Apply the derivative to the left-hand side.

Step 2.1:

Utilize the Product Rule, which is $\frac{d}{dx}(uv) = u\frac{dv}{dx} + v\frac{du}{dx}$, where $u = y$ and $v = x^2 + 16$. This gives us $y\frac{d}{dx}(x^2 + 16) + (x^2 + 16)\frac{d}{dx}(y)$.

Step 2.2:

Proceed to differentiate.

Step 2.2.1:

Invoke the Sum Rule to find the derivative of $x^2 + 16$ as $\frac{d}{dx}(x^2) + \frac{d}{dx}(16)$. This results in $y(2x + \frac{d}{dx}(16)) + (x^2 + 16)\frac{d}{dx}(y)$.

Step 2.2.2:

Apply the Power Rule, which tells us that $\frac{d}{dx}(x^n) = nx^{n-1}$ for $n = 2$. This simplifies to $y(2x + \frac{d}{dx}(16)) + (x^2 + 16)\frac{d}{dx}(y)$.

Step 2.2.3:

Recognize that the derivative of a constant is zero, so $\frac{d}{dx}(16) = 0$. This simplifies to $y(2x) + (x^2 + 16)\frac{d}{dx}(y)$.

Step 2.2.4:

Simplify the expression.

Step 2.2.4.1:

Combine $2x$ and $0$ to get $y(2x) + (x^2 + 16)\frac{d}{dx}(y)$.

Step 2.2.4.2:

Rearrange to place the constant $2$ before $y$: $2yx + (x^2 + 16)\frac{d}{dx}(y)$.

Step 2.3:

Express $\frac{d}{dx}(y)$ as $y'$.

Step 2.4:

Simplify further.

Step 2.4.1:

Apply the distributive property to get $2xy + x^2y' + 16y'$.

Step 2.4.2:

Reorder the terms to $2xy + x^2y' + 16y'$.

Step 3:

The derivative of a constant is zero, so $\frac{d}{dx}(32) = 0$.

Step 4:

Combine the derived terms to form the equation $2xy + x^2y' + 16y' = 0$.

Step 5:

Isolate $y'$.

Step 5.1:

Subtract $2xy$ from both sides to get $x^2y' + 16y' = -2xy$.

Step 5.2:

Factor out $y'$ from the left side.

Step 5.2.1:

Extract $y'$ from $x^2y'$ to get $y'(x^2) + 16y' = -2xy$.

Step 5.2.2:

Extract $y'$ from $16y'$ to get $y'(x^2) + y'(16) = -2xy$.

Step 5.2.3:

Factor out $y'$ completely to obtain $y'(x^2 + 16) = -2xy$.

Step 5.3:

Divide through by $x^2 + 16$ and simplify.

Step 5.3.1:

Divide each term to get $\frac{y'(x^2 + 16)}{x^2 + 16} = \frac{-2xy}{x^2 + 16}$.

Step 5.3.2:

Simplify the left side by canceling out the common factors.

Step 5.3.2.1:

Cancel the common factor to get $\frac{y'(\cancel{x^2 + 16})}{\cancel{x^2 + 16}} = \frac{-2xy}{x^2 + 16}$.

Step 5.3.2.1.2:

Reduce $y'$ over $1$ to get $y' = \frac{-2xy}{x^2 + 16}$.

Step 5.3.3:

Simplify the right side by bringing the negative sign to the front of the fraction.

Step 6:

Substitute $y'$ with $\frac{dy}{dx}$ to get the final result: $\frac{dy}{dx} = -\frac{2xy}{x^2 + 16}$.

Knowledge Notes:

  1. Product Rule: When taking the derivative of a product of two functions, $u$ and $v$, the derivative is $u'v + uv'$.

  2. Sum Rule: The derivative of the sum of two functions is the sum of their derivatives.

  3. Power Rule: For any real number $n$, the derivative of $x^n$ with respect to $x$ is $nx^{n-1}$.

  4. Constant Rule: The derivative of a constant is zero.

  5. Distributive Property: In an expression of the form $a(b + c)$, the distributive property allows us to expand this to $ab + ac$.

  6. Factoring: This involves taking a common factor out of terms to simplify expressions or equations.

  7. Simplifying Fractions: When a term in the numerator and the denominator are the same, they can be canceled out.

  8. Negative Sign in Fractions: A negative sign in the numerator or denominator of a fraction can be taken out in front of the fraction.

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