Math Problem Statement

y = (x^0.5 − 6x − 7)(x^−1 + x^−2) solve dy/dx

Solution

We are tasked with finding the derivative dydx\frac{dy}{dx} of the function:

y=(x0.56x7)(x1+x2)y = (x^{0.5} - 6x - 7)(x^{-1} + x^{-2})

We will use the product rule and the power rule to differentiate this function. The product rule states that if y=f(x)g(x)y = f(x)g(x), then:

dydx=f(x)g(x)+f(x)g(x)\frac{dy}{dx} = f'(x)g(x) + f(x)g'(x)

Step 1: Define f(x)f(x) and g(x)g(x)

Let:

  • f(x)=x0.56x7f(x) = x^{0.5} - 6x - 7
  • g(x)=x1+x2g(x) = x^{-1} + x^{-2}

Step 2: Differentiate f(x)f(x)

The derivative of f(x)=x0.56x7f(x) = x^{0.5} - 6x - 7 is:

f(x)=12x0.56f'(x) = \frac{1}{2}x^{-0.5} - 6

Step 3: Differentiate g(x)g(x)

The derivative of g(x)=x1+x2g(x) = x^{-1} + x^{-2} is:

g(x)=x22x3g'(x) = -x^{-2} - 2x^{-3}

Step 4: Apply the product rule

Now, applying the product rule:

dydx=f(x)g(x)+f(x)g(x)\frac{dy}{dx} = f'(x)g(x) + f(x)g'(x)

Substitute f(x)f'(x), f(x)f(x), g(x)g'(x), and g(x)g(x):

dydx=(12x0.56)(x1+x2)+(x0.56x7)(x22x3)\frac{dy}{dx} = \left(\frac{1}{2}x^{-0.5} - 6\right)(x^{-1} + x^{-2}) + (x^{0.5} - 6x - 7)(-x^{-2} - 2x^{-3})

Step 5: Simplify

Now we expand both terms:

  1. For (12x0.56)(x1+x2)\left(\frac{1}{2}x^{-0.5} - 6\right)(x^{-1} + x^{-2}):

=12x0.5x1+12x0.5x26x16x2= \frac{1}{2}x^{-0.5}x^{-1} + \frac{1}{2}x^{-0.5}x^{-2} - 6x^{-1} - 6x^{-2} =12x1.5+12x2.56x16x2= \frac{1}{2}x^{-1.5} + \frac{1}{2}x^{-2.5} - 6x^{-1} - 6x^{-2}

  1. For (x0.56x7)(x22x3)(x^{0.5} - 6x - 7)(-x^{-2} - 2x^{-3}):

=x0.5(x2)+x0.5(2x3)6x(x2)6x(2x3)7(x2)7(2x3)= x^{0.5}(-x^{-2}) + x^{0.5}(-2x^{-3}) - 6x(-x^{-2}) - 6x(-2x^{-3}) - 7(-x^{-2}) - 7(-2x^{-3}) =x1.52x2.5+6x1+12x2+7x2+14x3= -x^{-1.5} - 2x^{-2.5} + 6x^{-1} + 12x^{-2} + 7x^{-2} + 14x^{-3}

Step 6: Combine all terms

Now, combine all the terms from the two expansions:

dydx=12x1.5+12x2.56x16x2x1.52x2.5+6x1+12x2+7x2+14x3\frac{dy}{dx} = \frac{1}{2}x^{-1.5} + \frac{1}{2}x^{-2.5} - 6x^{-1} - 6x^{-2} - x^{-1.5} - 2x^{-2.5} + 6x^{-1} + 12x^{-2} + 7x^{-2} + 14x^{-3}

Step 7: Simplify further

Group the like terms:

dydx=(12x1.5x1.5)+(12x2.52x2.5)+(6x1+6x1)+(6x2+12x2+7x2)+14x3\frac{dy}{dx} = \left(\frac{1}{2}x^{-1.5} - x^{-1.5}\right) + \left(\frac{1}{2}x^{-2.5} - 2x^{-2.5}\right) + (-6x^{-1} + 6x^{-1}) + (-6x^{-2} + 12x^{-2} + 7x^{-2}) + 14x^{-3}

=12x1.532x2.5+13x2+14x3= -\frac{1}{2}x^{-1.5} - \frac{3}{2}x^{-2.5} + 13x^{-2} + 14x^{-3}

Final Answer:

dydx=12x1.532x2.5+13x2+14x3\frac{dy}{dx} = -\frac{1}{2}x^{-1.5} - \frac{3}{2}x^{-2.5} + 13x^{-2} + 14x^{-3}

Would you like to explore any part of this solution in more detail or have any questions?


Here are five related questions for further exploration:

  1. What is the interpretation of dydx\frac{dy}{dx} in this context?
  2. How would the solution change if there were additional terms in the original expression?
  3. Can you factor the result of dydx\frac{dy}{dx}?
  4. How would you integrate the derivative dydx\frac{dy}{dx}?
  5. How does the product rule apply in cases with more than two terms?

Tip: Always break down complex expressions by applying fundamental rules like the product rule and chain rule step by step.

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Math Problem Analysis

Mathematical Concepts

Calculus
Differentiation
Product Rule
Power Rule

Formulas

Product rule: (f(x)g(x))' = f'(x)g(x) + f(x)g'(x)
Power rule: (x^n)' = nx^(n-1)

Theorems

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Suitable Grade Level

Grades 11-12