作业帮求助几道因式分解题,（初中内容）1.a3b-45ab-4a2b2.x2+1/x2-63.(x-1)x(x+1)(x+2)-24
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求助几道因式分解题,（初中内容）1.a3b-45ab-4a2b2.x2+1/x2-63.(x-1)x(x+1)(x+2)-24
求助几道因式分解题,（初中内容）
1.a3b-45ab-4a2b
2.x2+1/x2-6
3.(x-1)x(x+1)(x+2)-24
求助几道因式分解题,（初中内容）1.a3b-45ab-4a2b2.x2+1/x2-63.(x-1)x(x+1)(x+2)-24
1.ab(a2-45+4a)=ab(a-5)(a+9)
2.由x2+1/x2可以联想到(a-b)2=a2+b2+2ab的公式.其中x2为a,1/x2为b,即得原式=(x-1/x)2-4=(x-1/x+2)(x-1/x-2)
3.(x-1)和(x+2)相乘,x和(x+1)相乘,得(x2+x-2)(x2+x)-24.设x2+x为A,则(A-2)A-24=(A+4)(A-6)=(x2+x+4)(x2+x-6)=(x2+x+4)(x+3)(x-2)
楼上的太复杂了,我初中是干奥数的——相信姐姐~这几题对初学者都蛮典型的、以后不懂可以到姐姐那留言,姐姐帮你做,乖啊~
.a3b-45ab-4a2b
=ab(a^2-45-4b)
2.x2+1/x2-6
=1/x2(x4-6x2+1)
3.(x-1)x(x+1)(x+2)-24
x(x + 1)(x - 1)(x + 2) - 24
= x(x^2 - 1)(x + 2) - 24
= x(x^3 + 2x^2 - x - 2) - 24
= ...
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.a3b-45ab-4a2b
=ab(a^2-45-4b)
2.x2+1/x2-6
=1/x2(x4-6x2+1)
3.(x-1)x(x+1)(x+2)-24
x(x + 1)(x - 1)(x + 2) - 24
= x(x^2 - 1)(x + 2) - 24
= x(x^3 + 2x^2 - x - 2) - 24
= x^4 + 2x^3 - x^2 - 2x - 24
= (x^4 - 2x^3) + 4x^3 - x^2 - 2x - 24
= x^3(x - 2) + 4x^3 - 8x^2 + 7x^2 - 2x - 24
= (x^3 + 4x^2)(x - 2) + (7x^2 - 14x) + (12x - 24)
= (x^3 + 4x^2 + 7x + 12)(x - 2)
= [(x^3 + 3x^2) + (x^2 + 3x) + (4x + 12)](x - 2)
= (x^2 + x + 4)(x + 3)(x - 2)
收起
1楼的第一题公因式没提好;
比较支持2楼的,毕竟人家是学奥数的......
1、ab(a+5)(a-9)
2、(x-1/x+2)(x-1/x-2)
3、（x2+x+4)(x+3)(x-2)