Math Problem Statement

Find dy/dx for y = √(1 + cos(x^2)).

Solution

Let's solve the problem dydx\frac{dy}{dx} for y=1+cos(x2)y = \sqrt{1 + \cos(x^2)}.

Solution:

The function given is: y=1+cos(x2)y = \sqrt{1 + \cos(x^2)}

Step 1: Rewrite the square root

Rewrite yy as: y=(1+cos(x2))1/2y = \left(1 + \cos(x^2)\right)^{1/2}

Step 2: Apply the chain rule

Differentiate both sides with respect to xx: dydx=12(1+cos(x2))1/2ddx(1+cos(x2))\frac{dy}{dx} = \frac{1}{2} \left(1 + \cos(x^2)\right)^{-1/2} \cdot \frac{d}{dx}(1 + \cos(x^2))

Step 3: Differentiate 1+cos(x2)1 + \cos(x^2)

The derivative of 11 is 00, and the derivative of cos(x2)\cos(x^2) is: ddxcos(x2)=sin(x2)ddx(x2)=sin(x2)2x\frac{d}{dx} \cos(x^2) = -\sin(x^2) \cdot \frac{d}{dx}(x^2) = -\sin(x^2) \cdot 2x

So: ddx(1+cos(x2))=2xsin(x2)\frac{d}{dx}(1 + \cos(x^2)) = -2x \sin(x^2)

Step 4: Substitute back

Substituting this into the expression for dydx\frac{dy}{dx}: dydx=12(1+cos(x2))1/2(2xsin(x2))\frac{dy}{dx} = \frac{1}{2} \left(1 + \cos(x^2)\right)^{-1/2} \cdot (-2x \sin(x^2))

Simplify: dydx=xsin(x2)1+cos(x2)\frac{dy}{dx} = \frac{-x \sin(x^2)}{\sqrt{1 + \cos(x^2)}}

Final Answer:

dydx=xsin(x2)1+cos(x2)\boxed{\frac{dy}{dx} = \frac{-x \sin(x^2)}{\sqrt{1 + \cos(x^2)}}}

Let me know if you'd like a more detailed explanation or have questions!


Here are 5 related questions to explore further:

  1. How do you apply the chain rule in similar problems with nested functions?
  2. What is the derivative of y=1cos(x2)y = \sqrt{1 - \cos(x^2)}?
  3. How would the derivative change if y=1+sin(x2)y = \sqrt{1 + \sin(x^2)}?
  4. Can you explain why ddxcos(x2)\frac{d}{dx} \cos(x^2) includes ddx(x2)\frac{d}{dx}(x^2)?
  5. What are some common applications of derivatives involving square roots in physics or engineering?

Tip: When working with square root functions, rewriting them as powers (e.g., u\sqrt{u} as u1/2u^{1/2}) makes differentiation easier!

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Math Problem Analysis

Mathematical Concepts

Differentiation
Chain Rule
Trigonometric Derivatives

Formulas

Derivative of √u is (1 / (2√u)) · (du/dx)
Derivative of cos(x) is -sin(x)
Chain Rule: d/dx[f(g(x))] = f'(g(x)) · g'(x)

Theorems

Chain Rule

Suitable Grade Level

Grades 11-12