# Math Help - Adjoint Operator

Let $V$ a inner product space, $T: V \rightarrow V$ a linear aplication and $T^*$ its adjoint.
Prove that $ker(TT^*+T^*T) = ker(T)\cap ker(T^*)$
2. Let $x\in V$ such that $T^*Tx+TT^*x =0$. We have $0\leq \langle Tx,Tx\rangle =\langle T^*Tx,x\rangle = -\langle TT^*x,x\rangle =-\langle T^*x,T^*x\rangle\leq 0$.