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

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(Created page with "<span class="exam">Find the equation of the tangent line to  <math style="vertical-align: -4px">y=3\sqrt{-2x+5}</math>  at  <math style="vertical-align: -4px">(...")
 
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<span class="exam">Find the equation of the tangent line to &nbsp;<math style="vertical-align: -4px">y=3\sqrt{-2x+5}</math>&nbsp; at &nbsp;<math style="vertical-align: -4px">(-2,9).</math>
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<span class="exam"> Find the derivatives of the following functions. Do not simplify.
  
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<span class="exam">(a)&nbsp; <math style="vertical-align: -16px">f(x)=\frac{(3x-5)(-x^{-2}+4x)}{x^{\frac{4}{5}}}</math>
  
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<span class="exam">(b)&nbsp; <math>g(x)=\sqrt{x}+\frac{1}{\sqrt{x}}+\sqrt{\pi}</math>&nbsp; for &nbsp;<math style="vertical-align: 0px">x>0.</math>
!Foundations: &nbsp;
 
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|The equation of the tangent line to &nbsp;<math style="vertical-align: -5px">f(x)</math>&nbsp; at the point &nbsp;<math style="vertical-align: -5px">(a,b)</math>&nbsp; is
 
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|
 
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|&nbsp; &nbsp; &nbsp; &nbsp; <math style="vertical-align: -5px">y=m(x-a)+b</math>&nbsp; where &nbsp;<math style="vertical-align: -5px">m=f'(a).</math>
 
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<hr>
  
'''Solution:'''
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[[009A Sample Midterm 3, Problem 4 Detailed Solution|'''<u>Detailed Solution with Background Information</u>''']]
  
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[[File:9ASM3P4.jpg|600px|thumb|center]]
!Step 1: &nbsp;
 
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|First, we need to calculate the slope of the tangent line.
 
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|Let &nbsp;<math style="vertical-align: -5px">f(x)=3\sqrt{-2x+5}.</math>
 
|-
 
|From Problem 3, we have
 
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|&nbsp; &nbsp; &nbsp; &nbsp; <math>f'(x)=-\frac{3}{\sqrt{-2x+5}}.</math>
 
|-
 
|Therefore, the slope of the tangent line is
 
|-
 
|
 
&nbsp; &nbsp; &nbsp; &nbsp; <math>\begin{array}{rcl}
 
\displaystyle{m} & = & \displaystyle{f'(-2)}\\
 
&&\\
 
& = & \displaystyle{-\frac{3}{\sqrt{-2(-2)+5}}}\\
 
&&\\
 
& = & \displaystyle{-\frac{3}{\sqrt{9}}}\\
 
&&\\
 
& = & \displaystyle{-1.}
 
\end{array}</math>
 
|}
 
  
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!Step 2: &nbsp;
 
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|Now, the tangent line has slope &nbsp;<math style="vertical-align: -1px">m=-1</math>
 
|-
 
|and passes through the point &nbsp;<math style="vertical-align: -5px">(-2,9).</math>
 
|-
 
|Hence, the equation of the tangent line is
 
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|&nbsp; &nbsp; &nbsp; &nbsp; <math>y=-1(x+2)+9.</math>
 
|}
 
 
 
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!Final Answer: &nbsp;
 
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|&nbsp; &nbsp; &nbsp; &nbsp; <math>y=-1(x+2)+9</math>
 
|-
 
|
 
|}
 
 
[[009A_Sample_Midterm_3|'''<u>Return to Sample Exam</u>''']]
 
[[009A_Sample_Midterm_3|'''<u>Return to Sample Exam</u>''']]

Revision as of 09:12, 7 November 2017

Find the derivatives of the following functions. Do not simplify.

(a) 

(b)    for  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 x>0.}


Detailed Solution with Background Information

9ASM3P4.jpg

Return to Sample Exam