let $T_1 : V \to W $ and $T_2 : V \to W $
how to show that $Kernel(T_1) \cap Kernel(T_2) \subset kernel(T1+T2) $?
let $T_1 : V \to W $ and $T_2 : V \to W $
how to show that $Kernel(T_1) \cap Kernel(T_2) \subset kernel(T1+T2) $?
Let $ x \in \ker T_1 \cap \ker T_2 $ be given. Then $T_1(x) = T_2(x) = 0$, so $$(T_1 + T_2)(x) = T_1(x) + T_2(x) = 0+0=0, $$ and thus $x \in \ker(T_1 + T_2) $