十字相乘法,1.9(a-b)²12(a²-b²)+4(a+b)²因式分解的结果A.(5a-b)² B.(5a+b)² C.(3a-2b)(3a+2b) D.(5a-2b)²2.(x-y)²-3(x-y)-40第一题打错了,应是9(a-b)²+12(a²-b²)+4(a+b)²还有
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![十字相乘法,1.9(a-b)²12(a²-b²)+4(a+b)²因式分解的结果A.(5a-b)² B.(5a+b)² C.(3a-2b)(3a+2b) D.(5a-2b)²2.(x-y)²-3(x-y)-40第一题打错了,应是9(a-b)²+12(a²-b²)+4(a+b)²还有](/uploads/image/z/11149396-52-6.jpg?t=%E5%8D%81%E5%AD%97%E7%9B%B8%E4%B9%98%E6%B3%95%2C1.9%28a-b%29%26%23178%3B12%28a%26%23178%3B-b%26%23178%3B%29%2B4%28a%2Bb%29%26%23178%3B%E5%9B%A0%E5%BC%8F%E5%88%86%E8%A7%A3%E7%9A%84%E7%BB%93%E6%9E%9CA.%EF%BC%885a-b%29%26%23178%3B+B.%EF%BC%885a%2Bb%29%26%23178%3B+C.%283a-2b%29%283a%2B2b%29+D.%285a-2b%29%26%23178%3B2.%28x-y%29%26%23178%3B-3%28x-y%29-40%E7%AC%AC%E4%B8%80%E9%A2%98%E6%89%93%E9%94%99%E4%BA%86%EF%BC%8C%E5%BA%94%E6%98%AF9%28a-b%29%26%23178%3B%2B12%28a%26%23178%3B-b%26%23178%3B%29%2B4%28a%2Bb%29%26%23178%3B%E8%BF%98%E6%9C%89)
十字相乘法,1.9(a-b)²12(a²-b²)+4(a+b)²因式分解的结果A.(5a-b)² B.(5a+b)² C.(3a-2b)(3a+2b) D.(5a-2b)²2.(x-y)²-3(x-y)-40第一题打错了,应是9(a-b)²+12(a²-b²)+4(a+b)²还有
十字相乘法,
1.9(a-b)²12(a²-b²)+4(a+b)²因式分解的结果
A.(5a-b)² B.(5a+b)² C.(3a-2b)(3a+2b) D.(5a-2b)²
2.(x-y)²-3(x-y)-40
第一题打错了,应是9(a-b)²+12(a²-b²)+4(a+b)²
还有3题
1.(2x+y)²+(2x+y)-2
2.x²+11xy+18y²
3.6x²-17x-10=( )(3x-10)
十字相乘法,1.9(a-b)²12(a²-b²)+4(a+b)²因式分解的结果A.(5a-b)² B.(5a+b)² C.(3a-2b)(3a+2b) D.(5a-2b)²2.(x-y)²-3(x-y)-40第一题打错了,应是9(a-b)²+12(a²-b²)+4(a+b)²还有
1.9(a-b)²+12(a²-b²)+4(a+b)²
=[3(a-b)]²+2[3(a-b)][2(a+b)]+[2(a+b)]²
=[3(a-b)+2(a+b)]²
=(5a-b)²
2.(x-y)²-3(x-y)-40
1 5
1 -8
=[(x-y)+5][(x-y)-8]
=(x-y+5)(x-y-8)
3.(2x+y)²+(2x+y)-2
1 2
1 -1
=(2x+y+2)(2x+y-1)
4.x²+11xy+18y²
1 2
1 9
=(x+2y)(x+9y)
3.6x²-17x-10=(2x+1 )(3x-10)
3 -10
2 1
2.(X-Y-8)(X-Y+5)
1.选A 9(a-b)²+12(a²-b²)+4(a+b)²=9a²-18ab+9b²+12a²-12b²+4a²+8ab+4b²=25a²-10ab+b²=5a-b)²
1、A
2、(x-y-8)(x-y+5)
3、(2x+y+2)(2x+y-1)
4、(x+2y)(x+9y)
5、2x+1