dy/dx

find the equations of tangents to the curve y2-2x3-4y+8=0 from the point (1,2)

4 Answers

62
Lokesh Verma ·

take (y-2)=m(x-1)

here the question says y2-2x3-4y+8=0

ie (y-2)2-2x3+4=0

m2(x-1)2-2x3+4=0

Now use the condition for repeated roots...

1
Aditya Balasubramanyam ·

Yes but i get a quadratic in m / cubic eq in x.. but that does'nt give the answer

1
Anupam ·

2ydy/dx-6x2-4dy/dx=0
dy/dx(2y-4)=6x2
dy/dx=6x2/(2y-4)
find dy/dx at (1,2)

dy/dx=∞
=>tangent || to y axis
→y=2 is tha required tangent

24
eureka123 ·

@anupam

tangent is not at the point (1,2)..it passes through that point[1]

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