Math Problem Statement

Find the derivative of the following expression: s = (4t + 2) / √(t² + 6)

Solution

To find the derivative of the given expression:

s=4t+2t2+6s = \frac{4t + 2}{\sqrt{t^2 + 6}}

we apply the quotient rule, which states:

ddt(uv)=vuuvv2\frac{d}{dt} \left( \frac{u}{v} \right) = \frac{v \cdot u' - u \cdot v'}{v^2}

Here:

  • u=4t+2u = 4t + 2 and v=t2+6=(t2+6)1/2v = \sqrt{t^2 + 6} = (t^2 + 6)^{1/2}

Step 1: Differentiate uu and vv

  1. u=4t+2    u=4u = 4t + 2 \implies u' = 4
  2. v=(t2+6)1/2    v=12(t2+6)1/22t=tt2+6v = (t^2 + 6)^{1/2} \implies v' = \frac{1}{2}(t^2 + 6)^{-1/2} \cdot 2t = \frac{t}{\sqrt{t^2 + 6}}

Step 2: Apply the quotient rule

Substitute into the quotient rule:

dsdt=t2+64(4t+2)tt2+6t2+6\frac{ds}{dt} = \frac{\sqrt{t^2 + 6} \cdot 4 - (4t + 2) \cdot \frac{t}{\sqrt{t^2 + 6}}}{t^2 + 6}

Step 3: Simplify the numerator

The numerator is:

t2+64(4t+2)tt2+6\sqrt{t^2 + 6} \cdot 4 - (4t + 2) \cdot \frac{t}{\sqrt{t^2 + 6}}

Rewrite it under a common denominator:

4(t2+6)(4t2+2t)t2+6\frac{4(t^2 + 6) - (4t^2 + 2t)}{\sqrt{t^2 + 6}}

Simplify the terms:

4(t2+6)(4t2+2t)=4t2+244t22t=242t4(t^2 + 6) - (4t^2 + 2t) = 4t^2 + 24 - 4t^2 - 2t = 24 - 2t

So the numerator becomes:

242tt2+6\frac{24 - 2t}{\sqrt{t^2 + 6}}

Step 4: Combine everything

The derivative is:

dsdt=242tt2+6t2+6=242t(t2+6)3/2\frac{ds}{dt} = \frac{\frac{24 - 2t}{\sqrt{t^2 + 6}}}{t^2 + 6} = \frac{24 - 2t}{(t^2 + 6)^{3/2}}

Final Answer:

dsdt=242t(t2+6)3/2\frac{ds}{dt} = \frac{24 - 2t}{(t^2 + 6)^{3/2}}

Would you like me to go into further details or explore another aspect of this problem?


Questions for further exploration:

  1. How does the quotient rule work in other scenarios with trigonometric functions?
  2. Can you find the critical points of s(t)s(t) by setting dsdt=0\frac{ds}{dt} = 0?
  3. What is the behavior of dsdt\frac{ds}{dt} as tt \to \infty?
  4. How does the chain rule contribute to the derivative of t2+6\sqrt{t^2 + 6}?
  5. Can you use logarithmic differentiation to solve the same problem?

Tip:

When solving complex derivatives, always simplify individual components (numerator and denominator) before combining!

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Math Problem Analysis

Mathematical Concepts

Calculus
Derivatives
Quotient Rule
Simplification

Formulas

Quotient Rule: d/dt (u/v) = (v * u' - u * v') / v²
Derivative of a square root function: d/dt(√f(t)) = (1/2) * f'(t) / √f(t)

Theorems

Quotient Rule
Chain Rule

Suitable Grade Level

Grades 11-12, College Calculus