Find the linearization $L(x,y,z)$ of the function $f(x,y,z)=e^{x}cos(yz)$ at the given points.

a$.(0,0,0)$

b$.(0,\frac{}{2},)$

c$.(0,\frac{3}{4},\frac{}{4})$

a$.L(x,y,z)=x2$

$($Type an exact answer.$)$

b$.L(x,y,z)=xyz-\frac{3}{2}1$

$($Type an exact answer.$)$

c$.L(x,y,z)=$

$($Type an exact ahnwer.$)$