Post

Created by @nathanedwards
 at October 31st 2023, 3:19:27 pm.

Question:

Find the derivative of the function

f(x)=sin⁡2(x2−3x)e2x2f(x) = \frac{\sin^2(x^2-3x)}{e^{2x^2}}

Step-by-Step Solution:

To find the derivative of the given function using the chain rule, we will break it down into simpler functions and apply the chain rule to each part.

Step 1: Identify the outermost function and the inner composite function.

In this case, the outermost function is the fraction and the inner composite function is the ratio of two functions - the numerator and the denominator.

Step 2: Differentiate the numerator and denominator separately using the chain rule.

Let's begin by finding the derivative of the numerator, which is sin⁡2(x2−3x)\sin^2(x^2-3x).

Using the chain rule, we can differentiate the square of sine function with respect to its inner function.

ddx(sin⁡2(u))=2sin⁡(u)cos⁡(u)⋅dudx\frac{d}{dx}(\sin^2(u)) = 2\sin(u)\cos(u) \cdot \frac{du}{dx}

Here, u=x2−3xu = x^2-3x.

So, ddx(sin⁡2(x2−3x))=2sin⁡(x2−3x)cos⁡(x2−3x)⋅ddx(x2−3x)\frac{d}{dx}\left(\sin^2(x^2-3x)\right) = 2\sin(x^2-3x)\cos(x^2-3x) \cdot \frac{d}{dx}(x^2-3x)

Expanding the derivative of the denominator using the chain rule, we get:

ddx(x2−3x)=ddx(x2)−ddx(3x)=2x−3\frac{d}{dx}(x^2-3x) = \frac{d}{dx}(x^2) - \frac{d}{dx}(3x) = 2x - 3

Substituting the above values, the derivative of the numerator becomes:

ddx(sin⁡2(x2−3x))=2sin⁡(x2−3x)cos⁡(x2−3x)⋅(2x−3)\frac{d}{dx}\left(\sin^2(x^2-3x)\right) = 2\sin(x^2-3x)\cos(x^2-3x) \cdot (2x - 3)

Step 3: Differentiate the denominator.

The denominator is e2x2e^{2x^2}.

To differentiate eue^u, we multiply it by the derivative of its exponent.

ddx(eu)=eu⋅dudx\frac{d}{dx}(e^u) = e^u \cdot \frac{du}{dx}

In this case, u=2x2u = 2x^2.

So, ddx(e2x2)=e2x2⋅ddx(2x2)\frac{d}{dx}(e^{2x^2}) = e^{2x^2} \cdot \frac{d}{dx}(2x^2)

Again, using the chain rule, the derivative of the exponent becomes:

ddx(2x2)=2⋅ddx(x2)=4x\frac{d}{dx}(2x^2) = 2 \cdot \frac{d}{dx}(x^2) = 4x

Substituting the above values, the derivative of the denominator becomes:

ddx(e2x2)=e2x2⋅4x=4x⋅e2x2\frac{d}{dx}(e^{2x^2}) = e^{2x^2} \cdot 4x = 4x \cdot e^{2x^2}

Step 4: Apply the chain rule to find the derivative of the entire function.

Using the quotient rule, the derivative of the function f(x)=sin⁡2(x2−3x)e2x2f(x) = \frac{\sin^2(x^2-3x)}{e^{2x^2}} can be written as:

f′(x)=g′(x)⋅h(x)−g(x)⋅h′(x)h(x)2f'(x) = \frac{g'(x) \cdot h(x) - g(x) \cdot h'(x)}{h(x)^2}

Where g(x)=sin⁡2(x2−3x)g(x) = \sin^2(x^2-3x) and h(x)=e2x2h(x) = e^{2x^2}.

Substituting the expressions for g′(x)g'(x), g(x)g(x), h′(x)h'(x), and h(x)h(x), we get:

f′(x)=(2sin⁡(x2−3x)cos⁡(x2−3x)⋅(2x−3)⋅e2x2)−(sin⁡2(x2−3x)⋅4x⋅e2x2)(e2x2)2f'(x) = \frac{(2\sin(x^2-3x)\cos(x^2-3x) \cdot (2x - 3) \cdot e^{2x^2}) - (\sin^2(x^2-3x) \cdot 4x \cdot e^{2x^2})}{(e^{2x^2})^2}

Simplifying the equation further, we have:

f′(x)=(4sin⁡(x2−3x)cos⁡(x2−3x)⋅(2x−3)⋅e2x2)−(4xsin⁡2(x2−3x)⋅e2x2)e4x2f'(x) = \frac{(4\sin(x^2-3x)\cos(x^2-3x) \cdot (2x - 3) \cdot e^{2x^2}) - (4x\sin^2(x^2-3x) \cdot e^{2x^2})}{e^{4x^2}}

Finally, we can simplify the expression further, if desired, by factoring out the common terms (2x−3)⋅e2x2(2x - 3) \cdot e^{2x^2} in both the numerator:

f′(x)=4sin⁡(x2−3x)cos⁡(x2−3x)⋅(2x−3)⋅e2x2[1−xsin⁡(x2−3x)]e4x2f'(x) = \frac{4\sin(x^2-3x)\cos(x^2-3x) \cdot (2x - 3) \cdot e^{2x^2}[1 - x\sin(x^2-3x)]}{e^{4x^2}}

Therefore, the derivative of the given function is:

f′(x)=4sin⁡(x2−3x)cos⁡(x2−3x)⋅(2x−3)⋅e2x2[1−xsin⁡(x2−3x)]e4x2f'(x) = \frac{4\sin(x^2-3x)\cos(x^2-3x) \cdot (2x - 3) \cdot e^{2x^2}[1 - x\sin(x^2-3x)]}{e^{4x^2}}