+0  
 
0
785
1
avatar+84 

Find by direct substitution

 

lim                              x-8

x --> y                  ------------------

                           x^2 + 13x + 42

 

 

a. limit does not exist

b. -1/240

c. 1/240

d. 0

e. infinity

 

 

 

 

 

 

Find 

 

lim                  'squareroot' 14+y - 'squareroot' 14

y --> 0            -----------------------------------------------

                                                 y

 

 

a. 'squareroot' 14 / 2

b. 'squareroot' 14 / 28

c. limit does not exist

d. 0

e. 'squareroot' 14 / 14

 Aug 29, 2016
 #1
avatar+118613 
+5

Find by direct substitution

 

lim                              x-8

x --> y                  ------------------

                           x^2 + 13x + 42

 

 

 

a. limit does not exist

b. -1/240

c. 1/240

d. 0

e. infinity

 

Are you sure you want x tends to y ??

If you do then just replace the x's with y's 

 

 

 

 

Find 

 

lim                  'squareroot' 14+y - 'squareroot' 14

y --> 0            -----------------------------------------------

                                                 y

 

I am using L'Hopital's rule to sove this:

If you do not know the rule you should watch this clip.

 

https://www.khanacademy.org/math/calculus-home/derivative-applications-calc/lhopitals-rule-calc/v/introduction-to-l-hopital-s-rule

 

 

\(\displaystyle\lim_{y\rightarrow0}\; \frac{\sqrt{14+y}+\sqrt{14}}{y}\\ =\displaystyle\lim_{y\rightarrow0}\; \frac{(14+y)^{1/2}+\sqrt{14}}{y}\\ \mbox{I am going to differentiate top and bottom separately with respect to y }\\ =\displaystyle\lim_{y\rightarrow0}\; \frac{(1/2)(14+y)^{-1/2}}{1}\\ =\displaystyle\lim_{y\rightarrow0}\; \frac{1}{2\sqrt{14+y}}\\ =\frac{1}{2\sqrt{14+0}}\\ =\frac{\sqrt{14}}{28}\\ \)

 Aug 29, 2016

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