十字相乘法分解因式 2x²-5x-3 -x²-2xy+15y² (a²+2a+3)²-13(a²+2a+3)+22
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![十字相乘法分解因式 2x²-5x-3 -x²-2xy+15y² (a²+2a+3)²-13(a²+2a+3)+22](/uploads/image/z/4084222-22-2.jpg?t=%E5%8D%81%E5%AD%97%E7%9B%B8%E4%B9%98%E6%B3%95%E5%88%86%E8%A7%A3%E5%9B%A0%E5%BC%8F+2x%26%23178%3B-5x-3+-x%26%23178%3B-2xy%2B15y%26%23178%3B+%28a%26%23178%3B%2B2a%2B3%29%26%23178%3B-13%28a%26%23178%3B%2B2a%2B3%29%2B22)
十字相乘法分解因式 2x²-5x-3 -x²-2xy+15y² (a²+2a+3)²-13(a²+2a+3)+22
十字相乘法分解因式 2x²-5x-3 -x²-2xy+15y² (a²+2a+3)²-13(a²+2a+3)+22
十字相乘法分解因式 2x²-5x-3 -x²-2xy+15y² (a²+2a+3)²-13(a²+2a+3)+22
2x²-5x-3=(x-3)(2x+1)
x -3
×
2x +1
-x²-2xy+15y²=(-x-5y)(x-3y)
-x -5y
×
x -3y
(a²+2a+3)²-13(a²+2a+3)+22 把(a²+2a+3)看成整体
=[(a²+2a+3)-2][(a²+2a+3)-11]
=(a²+2a+1)(a²+2a-8) 再分解
=(a+1)²(a+4)(a-2)