Chapter 5: Problem 17
If \(f(x)=m x^{2}+n x+p\), Then \(f^{\prime}(1)+f^{\prime}(4)-f^{\prime}(5)\) is equal to [MPPET-2008] (a) \(m\) (b) \(-m\) (c) \(n\) (d) \(-n\)
Short Answer
Expert verified
The expression evaluates to 0, which doesn't match any provided options.
Step by step solution
01
Identify the Problem
We need to compute the expression \(f^{\prime}(1) + f^{\prime}(4) - f^{\prime}(5)\), where \(f(x) = mx^2 + nx + p\). To proceed, we first need \(f'(x)\), the derivative of \(f(x)\).
02
Find the Derivative
Compute the derivative \(f'(x)\) of the function \(f(x) = mx^2 + nx + p\). Using standard derivative rules, the derivative is \(f'(x) = 2mx + n\).
03
Compute Specific Derivatives
Substitute the values 1, 4, and 5 into \(f'(x) = 2mx + n\) to find \(f'(1)\), \(f'(4)\), and \(f'(5)\). - \(f'(1) = 2m(1) + n = 2m + n\)- \(f'(4) = 2m(4) + n = 8m + n\)- \(f'(5) = 2m(5) + n = 10m + n\)
04
Substitute and Simplify
Substitute the computed values into the expression \(f'(1) + f'(4) - f'(5)\):\((2m + n) + (8m + n) - (10m + n)\).Simplify this to: \(2m + n + 8m + n - 10m - n = 0m + 0n = 0\).
05
Conclude
The result of the expression \(f'(1) + f'(4) - f'(5)\) is 0, meaning the expression evaluates to zero.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Functions
Quadratic functions are a type of polynomial function specifically of degree two. They have the general form:
- \(f(x) = ax^2 + bx + c\)
- \(a, b,\) and \(c\) are constants,
- \(a eq 0\) (to ensure it is a quadratic, not linear),
- \(x\) represents the variable.
Derivative Rules
In calculus, derivatives are used to measure how a function changes as its input changes. They are fundamental in understanding motion and change. For a quadratic function such as \( f(x) = mx^2 + nx + p \), the process to find the derivative involves several rules:
- The Power Rule: For any term \(x^n\), the derivative is \(nx^{n-1}\).
- The Constant Rule: The derivative of any constant is zero.
- The Sum Rule: The derivative of a sum is the sum of the derivatives.
- \( f'(x) = \frac{d}{dx}(mx^2) + \frac{d}{dx}(nx) + \frac{d}{dx}(p) = 2mx + n \).
Function Evaluation
Function evaluation involves substituting specific values into the function to determine the result. It's a critical step in calculus and mathematics in general. For a derivative \( f'(x) = 2mx + n \), evaluating it at specific points gives insight into the behavior of the original quadratic function at those points.
- To find \( f'(1) \), substitute \( x = 1 \) into the derivative: \( f'(1) = 2m(1) + n = 2m + n \).
- To find \( f'(4) \), substitute \( x = 4 \): \( f'(4) = 2m(4) + n = 8m + n \).
- To find \( f'(5) \), substitute \( x = 5 \): \( f'(5) = 10m + n \).
Expression Simplification
Simplification in mathematics involves reducing expressions to their simplest form to make them easier to work with. Simplifying the expression \( f'(1) + f'(4) - f'(5) \) requires basic arithmetic operations:
- Start with the values: \((2m + n) + (8m + n) - (10m + n)\).
- Combine like terms: \(2m + 8m - 10m + n + n - n \).
- Simplify: \(0m + 0n = 0\).