The curve
y =
1
x2 + 1
is called the witch of Agnesi after the Italian mathematician Maria Agnesi (1718−1799) who wrote one of the first books on calculus. This strange name is the result of a mistranslation of the Italian word la versiera, meaning "that which turns." Find equations of the tangent lines to the curve at
x = ±1.
x = −1
y =
x = 1
y =
