Chapter 2: Problem 7
Determine the slope of the tangent to each of the curves at the given point. a. \(y=3 x^{4},(1,3)\) b. \(y=\frac{1}{x^{-5}},(-1,-1)\) c. \(y=\frac{2}{x},(-2,-1)\) d. \(y=\sqrt{16 x^{3}},(4,32)\)
Short Answer
Expert verified
The slopes are 12, 5, -1/2, and 12 for curves a, b, c, and d respectively.
Step by step solution
01
Find the derivative for equation a
The function is given by \( y = 3x^4 \). To find the derivative, use the power rule which states that the derivative of \( x^n \) is \( nx^{n-1} \). Therefore, \( y' = 4 \cdot 3x^{4-1} = 12x^3 \). This function represents the slope of the tangent at any point \( x \).
02
Evaluate the slope for equation a at given point
Substitute \( x = 1 \) into the derivative \( y' = 12x^3 \) to find the slope of the tangent at point \((1, 3)\). This gives \( y' = 12(1)^3 = 12 \). Thus, the slope at point \((1,3)\) is \( 12 \).
03
Find the derivative for equation b
The function is given by \( y = \frac{1}{x^{-5}} \). Simplifying, \( y = x^{5} \). Using the power rule, the derivative is \( y' = 5x^{4} \).
04
Evaluate the slope for equation b at given point
Substitute \( x = -1 \) into \( y' = 5x^{4} \) to find the slope of the tangent at point \((-1, -1)\). This gives \( y' = 5(-1)^4 = 5 \). Thus, the slope at point \((-1,-1)\) is \( 5 \).
05
Find the derivative for equation c
The function is \( y = \frac{2}{x} \), which can be rewritten as \( y = 2x^{-1} \). Using the power rule, the derivative becomes \( y' = -2x^{-2} \) or \( y' = -\frac{2}{x^2} \).
06
Evaluate the slope for equation c at given point
Substitute \( x = -2 \) into \( y' = -\frac{2}{x^2} \) to find the slope of the tangent at point \((-2, -1)\). This calculates to \( y' = -\frac{2}{(-2)^2} = -\frac{2}{4} = -\frac{1}{2} \). Thus, the slope at point \((-2,-1)\) is \( -\frac{1}{2} \).
07
Find the derivative for equation d
The function is \( y = \sqrt{16x^3} = (16x^3)^{1/2} \). Use the chain rule and power rule to differentiate: \( y' = \frac{1}{2}(16x^3)^{-1/2} \cdot 48x^2 = \frac{24x^2}{\sqrt{16x^3}} \). Simplifying, this becomes \( y' = \frac{24x^2}{4x^{3/2}} = 6x^{1/2} \).
08
Evaluate the slope for equation d at given point
Substitute \( x = 4 \) into \( y' = 6x^{1/2} \) to find the slope at point \((4, 32)\). This yields \( y' = 6 \times 4^{1/2} = 6 \times 2 = 12 \). Thus, the slope at point \((4,32)\) is \( 12 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Tangent Line Slope
Finding the slope of a tangent line to a curve at a given point is a crucial concept in calculus. The slope tells us how steep the line is at that specific point.
- The tangent line "touches" the curve at precisely one point and has the same slope as the curve at that location.
- To find the slope of a tangent line, we first need the derivative of the function, as it represents the slope of the curve at any point.
- Once we have the derivative, we can substitute the x-coordinate of the given point into the derivative to find the slope at that specific point.
Power Rule
The Power Rule is a quick shortcut for differentiating functions of the form \( x^n \). It is one of the first derivative rules taught in calculus and is widely used because of its simplicity.To apply the power rule, follow these steps:
- Identify the exponent \( n \) in the expression \( x^n \).
- Multiply the entire expression by the exponent, resulting in \( n \cdot x^{n-1} \).
- Subtract one from the original exponent to finish the derivation: \( n-1 \).
Chain Rule
The Chain Rule is an essential technique for finding the derivatives of composite functions. A composite function is a function nested inside another function, such as \( (g(x))^n \). The chain rule allows us to take these apart for differentiation.When applying the chain rule:
- Differentiating the outer function first and leave the inner function untouched initially.
- Next, take the derivative of the inner function.
- Multiply the derivative of the outer function by the derivative of the inner function to get the composite derivative.
Derivative Evaluation
Evaluating derivatives at a specific point allows us to find the slope of the tangent line or the rate of change of the function at that point. It involves substituting the x-coordinate value into the derivative function.
Consider these steps to perform a derivative evaluation:
- First, ensure you have the correct derivative of the function.
- Substitute the x-value of the point you're interested in.
- Compute the result to find the slope of the tangent line at the point.