\(\left(x-y\right)^2-4=\left(x-y-2\right)\left(x-y+2\right)\)
\(9-\left(x-y\right)^2=\left(3-x+y\right)\left(3+x-y\right)\)
\(\left(x^2+4\right)^2-16x^2=\left(x^2-4x+4\right)\left(x^2+4x+4\right)=\left(x-2\right)^2\left(x+2\right)^2\)
\((X-y)^2-4=(x-y-2)(x-y+2)\)\((X^2+4)^2-16x^2=(x^2+4)^2-(4x)^2=(x^2+4-4x)(x^2+4+4x)\)
\(9-(x-y)^2=(3-x+y)(3+x-y)\)
a)(x-y)2-4=(x-y)2-22=(x-y-2)(x-y+2)
b)9-(x-y)2=32-(x-y)2=(3-x+y)(3+x-y)
c)(x2+4)2-16x2=(x2+4)2-(4x)2=(x2+4-4x)(x2+4+4x)=(x-2)2(x+2)2=(x2-2)2
\(\left(x-y\right)^2-4=\left(x-y-2\right)\left(x-y+2\right)\)
\(9-\left(x-y\right)^2=\left(3-x+y\right)\left(3+x-y\right)\)
\(\left(x^2+4\right)^2-16x^2=\left(x^2-4x+4\right)\left(x^2+4x+4\right)=\left(x-2\right)^2\cdot\left(x+2\right)^2\)