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40 votes
40 votes
Find the equation of the tangent line to f(x)=1/8 x^4-32/x^3 at X=2

User Legionar
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1 Answer

21 votes
21 votes

Given the function


f\mleft(x\mright)=(1)/(8)x^4-(32)/(x^3)

at the point x=2

the derivative of the function is


f^(\prime)(x)=(x^3)/(2)-(96)/(x^4)

derivative represent the slope of the tangent line

since x=2

then


f^(\prime)(2)=((2)^3)/(2)-(96)/((2)^4)
f^(\prime)(2)=4-6=-2

then m=-22

the line equation is


y-y1=m(x-x1)

where

m=-2

x1=2

y1=...


y1=(1)/(8)(2)^4-(32)/((2)^3)
y1=-2

y1=-2

then


y-y1=m(x-x1)
y-(-2)=-2(x-2)

solving for y


y+2=-2x+4
y=-2x+2

tangent line y = -2x+2

User Albi
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2.8k points