Chapter 3: Problem 57
Find the equation of the line tangent to the graph of \(f\) at \((1,1),\) where \(f\) is given by \(f(x)=2 x^{3}-2 x^{2}+1\)
Short Answer
Expert verified
The equation of the tangent line is \( y = 2x - 1 \).
Step by step solution
01
Determine the Derivative
To find the equation of the tangent line at a specific point, we must first determine the derivative of the function, as it gives us the slope of the tangent line. Let's find the derivative of \( f(x) = 2x^3 - 2x^2 + 1 \) using the power rule. The derivative is:\[ f'(x) = \frac{d}{dx}(2x^3) - \frac{d}{dx}(2x^2) + \frac{d}{dx}(1) = 6x^2 - 4x. \]
02
Evaluate the Derivative at the Point
Now that we have the derivative \( f'(x) = 6x^2 - 4x \), we can find the slope of the tangent line at the point \((1,1)\) by evaluating the derivative at \( x = 1 \).\[ f'(1) = 6(1)^2 - 4(1) = 6 - 4 = 2. \] So, the slope of the tangent line at \((1,1)\) is 2.
03
Use the Point-Slope Form of a Line
Now that we have the slope (2) and a point on the line \((1,1)\), we use the point-slope form to find the equation of the tangent line. The point-slope formula is given by:\[ y - y_1 = m(x - x_1), \] where \( m \) is the slope and \((x_1, y_1)\) is the point on the line. Substituting in the values, we get:\[ y - 1 = 2(x - 1). \]
04
Simplify the Equation
We simplify the equation \( y - 1 = 2(x - 1) \) to get it in slope-intercept form \( y = mx + b \). Begin by distributing the 2:\[ y - 1 = 2x - 2. \] Then add 1 to both sides to isolate \( y \):\[ y = 2x - 1. \] So, the equation of the tangent line is \( y = 2x - 1 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Calculus
Calculus is a branch of mathematics that studies how things change. It focuses on two primary concepts: differentiation and integration.
Differentiation is all about calculating the rate at which a function's value changes as its input changes. This is the foundation for understanding tangent lines, which are lines that just touch a curve at a single point without crossing it. Tangent lines show the instantaneous rate of change of the curve at that point.
In our exercise, we study a function's behavior at a particular point by using its derivative, representing differentiation.
Differentiation is all about calculating the rate at which a function's value changes as its input changes. This is the foundation for understanding tangent lines, which are lines that just touch a curve at a single point without crossing it. Tangent lines show the instantaneous rate of change of the curve at that point.
In our exercise, we study a function's behavior at a particular point by using its derivative, representing differentiation.
- Functions like \(f(x) = 2x^3 - 2x^2 + 1\) describe continuous change, which calculus helps to analyze precisely.
- Tangent lines are practical in calculus as they simplify the analysis of curves by providing linear approximations.
Derivatives
Derivatives are key in calculus because they tell us how a function changes at any given point. The derivative of a function represents the slope of the tangent line to the graph of the function.
For any function \(f(x)\), its derivative \(f'(x)\) gives us a formula that can find slopes at any \(x\)-value on the curve.
Using the power rule, which is a quick method for finding derivatives, our function \(f(x) = 2x^3 - 2x^2 + 1\) results in the derivative \(f'(x) = 6x^2 - 4x\).
For any function \(f(x)\), its derivative \(f'(x)\) gives us a formula that can find slopes at any \(x\)-value on the curve.
Using the power rule, which is a quick method for finding derivatives, our function \(f(x) = 2x^3 - 2x^2 + 1\) results in the derivative \(f'(x) = 6x^2 - 4x\).
- The power rule states that if \(f(x) = x^n\), then \(f'(x) = nx^{n-1}\).
- Applying the power rule involves multiplying the function's term by the exponent and decreasing the exponent by one.
Point-Slope Form
The point-slope form is useful for writing the equation of a line when you know exactly one point on the line and its slope. The formula is \(y - y_1 = m(x - x_1)\), where \((x_1, y_1)\) is the point and \(m\) represents the slope.
This form is incredibly helpful when dealing with tangent lines, as you often know both the slope (from derivatives) and a point (from the curve) and need to form the equation quickly.There is less worry about finding the \(y\)-intercept right away, as you focus on adjusting the base formula.
In the exercise, the slope \(m = 2\) and point \((1,1)\) come together to create \(y - 1 = 2(x - 1)\).
This form is incredibly helpful when dealing with tangent lines, as you often know both the slope (from derivatives) and a point (from the curve) and need to form the equation quickly.There is less worry about finding the \(y\)-intercept right away, as you focus on adjusting the base formula.
In the exercise, the slope \(m = 2\) and point \((1,1)\) come together to create \(y - 1 = 2(x - 1)\).
- After expanding and simplifying, you achieve the classic slope-intercept form, \(y = mx + b\), which in this case is \(y = 2x - 1\).
- The point-slope form is beneficial in educational settings for introducing students to line equations before complexity increases.