题目下列各式从左到右的变形为因式分解的是（ ）A.x2−y2=(x−y)2x^{2}-y^{2}=\left(x-y\right)^{2}x2−y2=(x−y)2B.x2−8x+16=(x−4)2x^{2}-8x+16=\left(x-4\right)^{2}x2−8x+16=(x−4)2C.(a+2)(a−1)=a2+a−2(a+2)\left(a-1\right)=a^{2}+a-2(a+2)(a−1)=a2+a−2D.a2−4+3a=(a+2)(a−2)+3aa^{2}-4+3a=\left(a+2\right)\left(a-2\right)+3aa2−4+3a=(a+2)(a−2)+3a知识点：分组分解法章节：数与式 / 因式分解
