Chapter 2: Problem 77
Find an equation of the line tangent to the graph of \(y=2^{x}+1\) at the point \((0,2)\).
Short Answer
Expert verified
The equation of the line tangent to the graph of \(y=2^x+1\) at the point \((0,2)\) is \(y=\ln{(2)}x+2\).
Step by step solution
01
Find the derivative of the given function
First, we need to find the derivative of the function \(y=2^x+1\). The derivative of a sum is the sum of the derivatives. The derivative of a constant is 0. To find the derivative of \(2^x\), we can use the chain rule which states that \(\frac{d}{dx}(a^u)=a^u \cdot \ln{(a)}\cdot u'\), where \(u\) is a function of x and \(a\) is a constant. So,
\[
\frac{dy}{dx} = \frac{d}{dx}(2^x+1) = \frac{d}{dx}(2^x) + \frac{d}{dx}(1)
\]
\[
\frac{dy}{dx}=2^x\cdot \ln{(2)}\cdot 1
\]
The derivative is \(y' = 2^x \cdot \ln{(2)}\).
02
Evaluate the derivative at the given point
Now we need to find the slope of the tangent line at the point \((0, 2)\) by evaluating the derivative at \(x=0\):
\[
y'(0) = 2^0 \cdot \ln{(2)} = 1\cdot \ln{(2)} = \ln{(2)}
\]
The slope is \(\ln{(2)}\).
03
Use the point-slope form
Finally, we can use the point-slope formula to find the equation of the tangent line. The point-slope formula is:
\[
y - y_1 = m(x - x_1)
\]
where \((x_1,y_1)\) is a point the line passes through and \(m\) is the slope. Plugging in our point \((0, 2)\) and the slope \(\ln{(2)}\):
\[
y-2=\ln{(2)}(x-0)
\]
04
Simplify the equation of the tangent line
Now, we can simplify the equation of the tangent line to get it in the slope-intercept form:
\[
y= \ln{(2)}x + 2
\]
The equation of the line tangent to the graph of \(y=2^x+1\) at the point \((0,2)\) is \(y=\ln{(2)}x+2\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Derivative
Understanding the derivative is key when finding the tangent line to a function. A derivative represents the rate at which a function is changing at any given point. In simple terms, it tells us how steep the graph is at that point. Let's consider the function given:
- Function: \( y = 2^x + 1 \)
- To differentiate this, we need the derivative of \( 2^x \).
- The derivative provides the slope of the tangent line at a specific point along the curve.
- Derivative: \( y' = 2^x \cdot \ln{(2)} \).
Chain Rule
The chain rule is a fundamental tool in calculus for finding derivatives of composite functions. A composite function is essentially a function within another function. If you encounter a situation where the function's exponent is another function of \( x \), the chain rule comes in handy.
- The chain rule formula is \( \frac{d}{dx}(a^u) = a^u \cdot \ln(a) \cdot u' \), where \( u \) is a function of \( x \).
- Use of Chain Rule: \( y' = 2^x \cdot \ln(2) \cdot 1 \).
Point-Slope Form
The point-slope form is vital in writing the equation of a line when you know a point on the line and its slope. This form is given by the formula:
- Formula: \( y - y_1 = m(x - x_1) \)
- Point: \((x_1, y_1) = (0, 2) \)
- Slope: \( m = \ln(2) \)
- Initial Equation: \( y - 2 = \ln(2)(x - 0) \)
Exponential Functions
Exponential functions are mathematical expressions involving exponents where the base is a constant and the exponent is a variable. These types of functions grow very quickly, which often results in steep slopes.
- General Form: \( y = a^x + b \)
- Growth Nature: Changes in \( x \) result in exponential changes in \( y \).
- Additional Constant: The +1 shifts the entire curve up by 1 unit.
- Base of Exponent: The base is 2, which affects the rate of growth; hence, as \( x \) increases, \( y \) increases exponentially.