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Let f(4)=8 and f'(4)=6. Then the equation of the tangent line to the graph of y=f(x) at x=4 is _____________.

 

I have no idea how to even begin this question indecision any help is appreciated 

 Feb 13, 2016

Best Answer 

 #1
avatar+129849 
+10

We have a point (4,8) ......  and the slope of the curve at that point  = 6

 

So...the equation of the tangent line to that point  will have the same slope as the curve at that point....and we have

 

 

y - 8  = 6(x - 4)

 

y - 8  = 6x - 24      add 8 to both sides

 

y  = 6x - 16

 

 

 

cool cool cool

 Feb 13, 2016
 #1
avatar+129849 
+10
Best Answer

We have a point (4,8) ......  and the slope of the curve at that point  = 6

 

So...the equation of the tangent line to that point  will have the same slope as the curve at that point....and we have

 

 

y - 8  = 6(x - 4)

 

y - 8  = 6x - 24      add 8 to both sides

 

y  = 6x - 16

 

 

 

cool cool cool

CPhill Feb 13, 2016
 #2
avatar+270 
+10

Doh!

 

I wasn't thinking f(4)=8 is basically stating the point (4,8)..

 

it's too late at night >_> I need sleep.. haha, thanks CPhill

gretzu  Feb 13, 2016

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