Cracking The Ap Calculus ab Exam 2018

(Marvins-Underground-K-12) #1

First, we need to find the y-coordinates that correspond to x = 1. We plug x = 1 into x^2 y − 4x +


y^2     =   2,  and rearrange   a   little, and we  get y^2     +   y   −   6   =   0.

Next, we factor the quadratic to get (y + 3)(y − 2) = 0, so we will be finding tangent lines at the
coordinates (1, −3) and (1, 2).


At (1, −3), we get = = = −2.


Therefore, the equation of the tangent line is y + 3 = −2(x − 1).


At (1, 2), we get = = .


Therefore, the equation of the tangent line is y = 2.

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