We are asked to use the quadratic approximation of
at the point
to approximate
. The formula for this quadratic approximation, which we denote by
, is given by
. We already know that
, so we need only find
. To do so, we apply the power rule twice, and find that:
, and then
Substituting this information into our formula for
, we have
. Then, to estimate the value of
, we plug-in
into our quadratic approximation. This gives
.