\(13,\\ a,=3\left(x-5y\right)\\ b,=x\left(x^2+2x+1\right)=x\left(x+1\right)^2\\ c,=16-\left(x-y\right)^2=\left(16+x-y\right)\left(16-x+y\right)\\ 14,\\ a,=\left(x-4\right)\left(x+4\right):\left(x+4\right)=x-4\\ b,\Rightarrow\left(x-3\right)^2=0\Rightarrow x=3\)