题目下列各式从左到右的变形中,属于因式分解的是（ ）A.6x+12y+3=3(2x+4y)6x+12y+3=3\left(2x+4y\right)6x+12y+3=3(2x+4y)B.a2−1=(a−1)2a^{2}-1=\left(a-1\right)^{2}a2−1=(a−1)2C.x2+x+14=(x+12)2{x}^{2}+x+\frac{1}{4}={(x+\frac{1}{2})}^{2}x2+x+41=(x+21)2D.2x2−1=2(x−1)(x+1)2x^{2}-1=2\left(x-1\right)\left(x+1\right)2x2−1=2(x−1)(x+1)知识点：十字相乘法章节：数与式 / 因式分解
