\(a=\left(x+1\right)^2-\left(4y\right)^2=\left(x+1-4y\right)\left(x+1+4y\right)\)
\(b=\left(x+3\right)^2-y^2=\left(x+3+y\right)\left(x+3-y\right)\)
\(c=\left(2x+1\right)^2-\left(3y\right)^2=\left(2x+1-3y\right)\left(2x+1+3y\right)\)
\(d=\left(x+3y\right)^2-\left(5z\right)^2=\left(x+3y-5z\right)\left(x+3y+5z\right)\)