几道数学初一的因式分解,求啦,在线的数学高手们速度!我急着要! 好的,速度又快的,正确率高的,加分!
\u4e00\u9053\u6570\u5b66\u56e0\u5f0f\u5206\u89e3\u9898(\u521d\u4e00\uff09 \u901f\u5ea6\u554a\u554a16\uff08a-b\uff09^2 - 9\uff08a+b\uff09^2
\uff1d\uff084a-4b\uff09^2-\uff083a+3b\uff09^2
=(4a-4b+3a+3b)(4a-4b-3a-3b)
=(7a-b)(a-7b)
1.D.-x\uff08x²-x-1\uff09
2. D.-42
3.C.m\uff08a-2\uff09\uff08m-1\uff09
4.A.\ufe59x^n\ufe5a-1
\u8ba1\u7b97\u9898
5.m²\uff08a-2\uff09+m\uff082-a\uff09
=m²\uff08a-2\uff09-m\uff08a-2\uff09
=m\uff08a-2\uff09(m-1)
6.a\uff08x-y\uff09-b\uff08y-x\uff09²
=a\uff08x-y\uff09-b\uff08x-y\uff09²
=(x-y)[a-b(x-y)]
=(x-y)(a-bx+by)
7.\u82e5x+y=3\uff0cxy=-4.\u3002\u6c422x²y+2xy²\u7684\u503c\u3002
\uff08\u7528\u7b80\u4fbf\u65b9\u6cd5\u8ba1\u7b97\uff09
2x²y+2xy²
=2xy(x+y)
=2*(-4)*3
=-24
8. 1.23*48+1.23*65-1.23*13
=1.23*(48+65-13)
=1.23*100
=123
9. 18.6*0.125+13.4*1/8
=18.6*0.125+13.4*0.125
=(18.6+13.4)*0.125
=32*0.125
=32*1/8
=4
10.\u5df2\u77e5x²+x-1=0\uff0c\u6c42x³+2x²+2009\u7684\u503c
x²+x-1=0
x²+x=1
x³+2x²+2009
=x³+x²+x²+2009
=x(x²+x)+x²+2009
=x+x²+2009
=1+2009
=2010
12 = 3 * 4 = 2 * 6 = 1*12
10 = 2 * 5 = 1*10
但要凑到7就用这几个比较去算了。。。
3 2
4 5
这个要注意12和10分解出的因子要放在同一列,因为10前面有个负号,所以要在2或5只间选择一个用上, 注意 一定要是对角线的才能相乘
3 * 5 - 2 * 4 = 7
所以应该是这样
3 -2
4 5
然后把x和y对应写上去
3x -2y
4x 5y
最后写出式子:(3x-2)(4x-5)
方法就是这样,其他的你自己去练吧,数学就是要多练
12x²+7xy-10y²=(3x-2y)(4x+5y)
12t²-7t+1=(3t-1)(4t-1)
a²+6a-(b-2)²+9=(a+3)²-(b-2)²=(a+b+1)(a-b+5)
3a(a+b)(a-b)-2b(b+a)=(a+b)(3a²-3ab-2b)
-4xm次方+3xm+1次方y3n次方-xm+2次方yn次方=xm次方(-4+3xy3n次方-x²yn次方)
4a²-2a-b²-b=(2a+b)×(2a-b)-(2a+b)
=(2a+b)(2a-b-1)
12x平方+7xy-10y平方=(3x-2y)(4x+5y)
12t平方-7t+1=(3t-1)(4t-1)
a平方+6a-(b-2)平方+9=()()
3a(a+b)(a-b)-2b(b+a)=(a+b)(3a^2-3ab-2b)
-4xm次方+3xm+1次方y3n次方-xm+2次方yn次方=没看懂
4a平方-2a-b平方-b=(4a^2-b^2)-(2a+b)=(2a+b)(2a-b-1)
12x^2+7xy-10y^2=(3x-2y)(4x-5y) 十字相乘法
12t^2-7t+1=(3t-1)(4t-1) 十字相乘法
12x平方+7xy-10y平方
a^2+6a-(b-2)^2+9=(a+b)(3a^2-3ab-2b)
-4x^m+3x^(m+1)y^(3n)-x^(m+2)y^n=x^m(-4-3xy^3n-x^2y^n)
4a^2-2a-b^2-b=(2a+b)(2a-b-1)
(3x-2)(4x-5)
(3t-1)(4t-1)
(3a^2-3ab-2b)(a+b)
x^m(-4+3xy^3n-x^2y^n)
(2a-b-1)(2a+b)
告诉你方法先提公因式,然后找平方差公式和完全平方公式,楼下答案是对的,但应当不符合初一学生标准,貌似像十字相乘法
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