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Find the equation to the tangent line of

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y = (x^3 -1) * (x^2 + 1)^4 at the point where x = -1?

asked Apr 16, 2013 in CALCULUS by chrisgirl Apprentice

1 Answer

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The curve y = (x3 - 1)×(x2 + 1)4

Substitute x = -1 in the given curve

y = (-1 - 1)(1 + 1)4

Simplify

y = -32

The slope of the curve :m = dy / dx at the point (-1, -32)

Apply the derivative to each side with respective x for given curve

dy / dx = (x3 - 1)4(x2 + 1)3 (2x) + 3x2(x2 + 1)4

dy / dx at x = -1

Substitute x = -1 in the dy / dx

dy / dx = (-1 - 1)4(1 + 1)3 (-2) + 3(1 + 1)4

Simplify

dy / dx at x = -1: m = 176

The slope m and the point (x1 , y1) then the tangent line equation : y - y1 = m(x - x1)

Substitute m = 176 and x1 = -1 , y1 = -32 in the tangent line

y - (-32) = 176(x - (-1)

y + 32 = 176(x + 1)

y + 32 = 176x + 176

y = 176x + 144

or

176x - y = -144.

 

 

answered Apr 19, 2013 by diane Scholar

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