Prove Weierstrass M-test. Prove by induction that the function
f(x)=exp(-(1)/(x^(2)))
for
x!=0
and
f(0)=0
has derivatives of all orders at every point in
R
and that all of these derivatives vanish at
x=0
. Hence this function is not given by its Taylor expansion about
x=0
. Prove that if
\sum_(n=0)^(\infty ) a_(n)x^(n)
converges for
x=x_(0)
and diverges for
x=x_(1)
, then a.
\sum_(n=0)^(\infty ) a_(n)x^(n)
converges absolutely for
|x|<|x_(0)|
, and b.
\sum_(n=0)^(\infty ) a_(n)x^(n)
diverges for
|x|>|x_(1)|
. How could one use the Ratio Test to establish criteria for the radius of convergence? Suppose that
\sum a_(n)
diverges and that
{a_(n)}
is bounded. Prove the radius of convergence of the power series
\sum a_(n)x^(n)
is equal to 1 . Write the Taylor series for
\sqrt(1-x)
centered at 0 . Prove that the series converges to
\sqrt(1-x)
for
xin(-1,0]
.