$3\mathrm{.}2$ Show that

$($a$)\frac{de{l}^2}{\text{d}\text{e}\text{l}\text{x}\text{d}\text{e}\text{l}\text{y}}{|}_{i,j}||=\frac{{}_{i+1,j+1}-{}_{i-1,j+1}-{}_{i+1,j-1}+{}_{i-1,j-1}}{4xy}+0[(x{)}^2,(y{)}^2]$

$($b$)\frac{de{l}^4}{del{x}^4}{|}_{i,j}||=\frac{3{}_{i,j}-14{}_{i-1,j}+26{}_{i-2,j}-24{}_{i-3,j}+11{}_{i-4,j}-2{}_{i-5,j}}{(x{)}^4}+0(x{)}^2$

$($c$)\frac{de{l}^4}{del{x}^4}{|}_{i,j}||=\frac{{}_{i,j}-4{}_i}{(x{)}^4}=1,j+6{}_{i-2,j}-4{}_{i-3,j}+{}_{i-4,j}+0(x)$