题目下列由左到右的变形,是因式分解的为（ ）A.(x+4)(x−4)=x2−16(x+4)\left(x-4\right)=x^{2}-16(x+4)(x−4)=x2−16B.x2−y2−1=(x+y)(x−y)−1x^{2}-y^{2}-1=\left(x+y\right)\left(x-y\right)-1x2−y2−1=(x+y)(x−y)−1C.x2−4xy+4y2=(x−2y)2x^{2}-4xy+4y^{2}=\left(x-2y\right)^{2}x2−4xy+4y2=(x−2y)2D.x2−2x+1=x(x−2)+1x^{2}-2x+1=x\left(x-2\right)+1x2−2x+1=x(x−2)+1知识点：十字相乘法章节：数与式 / 因式分解
