Difference between revisions of "009A Sample Midterm 3, Problem 4"

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|From Problem 3, we have  
 
|From Problem 3, we have  
 
|-
 
|-
|&nbsp; &nbsp; &nbsp; &nbsp; <math>f'(x)=\frac{-3}{\sqrt{-2x+5}}.</math>
+
|&nbsp; &nbsp; &nbsp; &nbsp; <math>f'(x)=-\frac{3}{\sqrt{-2x+5}}.</math>
 
|-
 
|-
 
|Therefore, the slope of the tangent line is  
 
|Therefore, the slope of the tangent line is  
Line 32: Line 32:
 
\displaystyle{m} & = & \displaystyle{f'(-2)}\\
 
\displaystyle{m} & = & \displaystyle{f'(-2)}\\
 
&&\\
 
&&\\
& = & \displaystyle{\frac{-3}{\sqrt{-2(-2)+5}}}\\
+
& = & \displaystyle{-\frac{3}{\sqrt{-2(-2)+5}}}\\
 
&&\\
 
&&\\
& = & \displaystyle{\frac{-3}{\sqrt{9}}}\\
+
& = & \displaystyle{-\frac{3}{\sqrt{9}}}\\
 
&&\\
 
&&\\
 
& = & \displaystyle{-1.}
 
& = & \displaystyle{-1.}

Revision as of 09:21, 13 March 2017

Find the equation of the tangent line to  Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle y=3\sqrt{-2x+5}}   at  Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle (-2,9).}


Foundations:  
The equation of the tangent line to  Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle f(x)}   at the point  Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle (a,b)}   is
        Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle y=m(x-a)+b}   where  Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle m=f'(a).}


Solution:

Step 1:  
First, we need to calculate the slope of the tangent line.
Let  Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle f(x)=3\sqrt{-2x+5}.}
From Problem 3, we have
        Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle f'(x)=-\frac{3}{\sqrt{-2x+5}}.}
Therefore, the slope of the tangent line is

        Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \begin{array}{rcl} \displaystyle{m} & = & \displaystyle{f'(-2)}\\ &&\\ & = & \displaystyle{-\frac{3}{\sqrt{-2(-2)+5}}}\\ &&\\ & = & \displaystyle{-\frac{3}{\sqrt{9}}}\\ &&\\ & = & \displaystyle{-1.} \end{array}}

Step 2:  
Now, the tangent line has slope  Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle m=-1}
and passes through the point  Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle (-2,9).}
Hence, the equation of the tangent line is
        Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle y=-1(x+2)+9.}


Final Answer:  
        Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle y=-1(x+2)+9}

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