因式分解1.-4x²+4xy-y² 2.4t²-12t+9一共四题 3.16m²-72mn+81n² 4.4a²-4a(b+c)+(b+c)²

因式分解1.-4x²+4xy-y² 2.4t²-12t+9一共四题 3.16m²-72mn+81n² 4.4a²-4a(b+c)+(b+c)²
因式分解1.-4x²+4xy-y² 2.4t²-12t+9
一共四题 3.16m²-72mn+81n² 4.4a²-4a(b+c)+(b+c)²

因式分解1.-4x²+4xy-y² 2.4t²-12t+9一共四题 3.16m²-72mn+81n² 4.4a²-4a(b+c)+(b+c)²
1.-4x²+4xy-y² =﹣﹛﹙2x﹚²﹣2×2x·y＋y² ﹜=﹣(2x-y)²
2.4t²-12t+9=﹙2t﹚²-2×2t·3+3²=（2t-3)²
3.16m²-72mn+81n² =﹙4m﹚²-2×4m×9n+﹙9n﹚² =﹙4m-9n)²
4.4a²-4a(b+c)+(b+c)²=﹙2a﹚²-2×2a(b+c)+(b+c)²=﹙2a﹣b﹣c)²