a) Find, in terms of a, the equations of the lines tangent to these curves ) Find, in terms of a, the y-intercepts of the tangent lines at r = -1. c) Find the .r-intercepts of the tangent lines at a = -1.

Advanced Engineering Mathematics
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Author:Erwin Kreyszig
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Chapter2: Second-order Linear Odes
Section: Chapter Questions
Problem 1RQ
Question
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Part d: Find, in terms of a, the area enclosed by the graph of f(x), the tangent line at x=-1 and the y-axis.

**Calculus Problem on Tangent Lines and Areas**

**Problem Statement:**
Let \( f(x) = a(7 - x^2) \) for all \( a \neq 0 \).

1. **Find, in terms of \( a \), the equations of the lines tangent to these curves at \( x = -1 \).**

2. **Find, in terms of \( a \), the \( y \)-intercepts of the tangent lines at \( x = -1 \).**

3. **Find the \( x \)-intercepts of the tangent lines at \( x = -1 \).**

4. **Find, in terms of \( a \), the area enclosed by the graph of \( f(x) \), the tangent line at \( x = -1 \), and the \( y \)-axis.**

**Solutions:**

_(a) Find, in terms of \( a \), the equations of the lines tangent to these curves at \( x = -1 \)._

1. **Deriving the tangent lines:**
   Since \( a > 0 \), that means \( a \neq 0 \) and these will become our two equations.
   
2. **Find the slope by finding the derivative:**
   \[
   f'(x) = (7a - ax^2)' = -2ax
   \]
   \(*Note: The term \( 7a \) becomes zero since \( a \) is considered to be a constant\)

3. **Plug in \( x = -1 \) to find the slope:**
   \[
   f'(-1) = -2a(-1) \Rightarrow m = 2a
   \]

4. **Find the y-coordinate at \( x = -1 \):**
   \[
   f(-1) = a(7 - (-1)^2) = 6a
   \]

5. **With the coordinates \((-1, 6a)\), use the point-slope form of the equation of a line:**
   \[
   y - 6a = 2a(x + 1)
   \]
   Simplifying, we get:
   \[
   y = 2ax + 8a
   \]

_(b) Find, in terms of \( a \), the \( y \)-intercepts of the tangent lines at \( x = -
Transcribed Image Text:**Calculus Problem on Tangent Lines and Areas** **Problem Statement:** Let \( f(x) = a(7 - x^2) \) for all \( a \neq 0 \). 1. **Find, in terms of \( a \), the equations of the lines tangent to these curves at \( x = -1 \).** 2. **Find, in terms of \( a \), the \( y \)-intercepts of the tangent lines at \( x = -1 \).** 3. **Find the \( x \)-intercepts of the tangent lines at \( x = -1 \).** 4. **Find, in terms of \( a \), the area enclosed by the graph of \( f(x) \), the tangent line at \( x = -1 \), and the \( y \)-axis.** **Solutions:** _(a) Find, in terms of \( a \), the equations of the lines tangent to these curves at \( x = -1 \)._ 1. **Deriving the tangent lines:** Since \( a > 0 \), that means \( a \neq 0 \) and these will become our two equations. 2. **Find the slope by finding the derivative:** \[ f'(x) = (7a - ax^2)' = -2ax \] \(*Note: The term \( 7a \) becomes zero since \( a \) is considered to be a constant\) 3. **Plug in \( x = -1 \) to find the slope:** \[ f'(-1) = -2a(-1) \Rightarrow m = 2a \] 4. **Find the y-coordinate at \( x = -1 \):** \[ f(-1) = a(7 - (-1)^2) = 6a \] 5. **With the coordinates \((-1, 6a)\), use the point-slope form of the equation of a line:** \[ y - 6a = 2a(x + 1) \] Simplifying, we get: \[ y = 2ax + 8a \] _(b) Find, in terms of \( a \), the \( y \)-intercepts of the tangent lines at \( x = -
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