\(A=\left(5x\right)^2-1^2=\left(5x-1\right)\left(5x+1\right)\)
\(B=\left(x-2\right)^2-y^2=\left(x-y-2\right)\left(x+y-2\right)\)
\(C=x\left(x^2+8x+16\right)=x\left(x+4\right)^2\)
\(D=\left(x-y\right)\left(x+y\right)-3\left(x+y\right)=\left(x-y-3\right)\left(x+y\right)\)
\(E=\left(3x\right)^2-\left(y^2-10y+25\right)=\left(3x\right)^2-\left(y-5\right)^2\)
\(=\left(3x-y+5\right)\left(3x+y-5\right)\)
\(F=x^2+x+7x+7=x\left(x+1\right)+7\left(x+1\right)=\left(x+1\right)\left(x+7\right)\)
\(G=3x^2+3x-5x-5=3x\left(x+1\right)-5\left(x+1\right)=\left(x+1\right)\left(3x-5\right)\)
\(H=x^2+x-5x-5=x\left(x+1\right)-5\left(x+1\right)=\left(x-5\right)\left(x+1\right)\)
