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  初中因式分解化简的题

  初中因式分解化简的题

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2019-03-18 12:51
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  1.5ax+5bx+3ay+3by

  解法:=5x(a+b)+3y(a+b)

  =(5x+3y)(a+b)

  2.x^3-x^2+x-1

  解法:=(x^3-x^2)+(x-1)

  =x^2(x-1)+(x-1)

  =(x-1)(x^2+1)

  3.x2-x-y2-y

  解法:=(x2-y2)-(x+y)

  =(x+y)(x-y)-(x+y)

  =(x+y)(x-y-1)

  bc(b+c)+ca(c-a)-ab(a+b)

  =bc(c-a+a+b)+ca(c-a)-ab(a+b)

  =bc(c-a)+bc(a+b)+ca(c-a)-ab(a+b)

  =bc(c-a)+ca(c-a)+bc(a+b)-ab(a+b)

  =(bc+ca)(c-a)+(bc-ab)(a+b)

  =c(c-a)(b+a)+b(a+b)(c-a)

  =(c+b)(c-a)(a+b).

  x^2+3x-40

  =x^2+3x+2.25-42.25

  =(x+1.5)^2-(6.5)^2

  =(x+8)(x-5).

  (x^2+x+1)(x^2+x+2)-12时,可以令y=x^2+x,则

  原式=(y+1)(y+2)-12

  =y^2+3y+2-12=y^2+3y-10

  =(y+5)(y-2)

  =(x^2+x+5)(x^2+x-2)

  =(x^2+x+5)(x+2)(x-1).

  (1+y)^2-2x^2(1+y^2)+x^4(1-y)^2

  原式=(1+y)^2+2(1+y)x^2(1+y)+x^4(1-y)^2-2(1+y)x^2(1-y)-2x^2(1+y^2)

  =[(1+y)+x^2(1-y)]^2-2(1+y)x^2(1-y)-2x^2(1+y^2)

  =[(1+y)+x^2(1-y)]^2-(2x)^2

  =[(1+y)+x^2(1-y)+2x]·[(1+y)+x^2(1-y)-2x]

  =(x^2-x^2y+2x+y+1)(x^2-x^2y-2x+y+1)

  =[(x+1)^2-y(x^2-1)][(x-1)^2-y(x^2-1)]

  =(x+1)(x+1-xy+y)(x-1)(x-1-xy-y)

  x^5+3x^4y-5x^3y^2+4xy^4+12y^5

  原式=(x^5+3x^4y)-(5x^3y^2+15x^2y^3)+(4xy^4+12y^5)

  =x^4(x+3y)-5x^2y^2(x+3y)+4y^4(x+3y)

  =(x+3y)(x^4-5x^2y^2+4y^4)

  =(x+3y)(x^2-4y^2)(x^2-y^2)

  =(x+3y)(x+y)(x-y)(x+2y)(x-2y)

  分解因式m+5n-mn-5m

  m+5n-mn-5m=m-5m-mn+5n

  =(m-5m)+(-mn+5n)

  =m(m-5)-n(m-5)

  =(m-5)(m-n)

  分解因式bc(b+c)+ca(c-a)-ab(a+b)

  bc(b+c)+ca(c-a)-ab(a+b)=bc(c-a+a+b)+ca(c-a)-ab(a+b)

  =bc(c-a)+ca(c-a)+bc(a+b)-ab(a+b)

  =c(c-a)(b+a)+b(a+b)(c-a)

  =(c+b)(c-a)(a+b)

  1.(2a-b)²+8ab

  2.y²-2y-x²+1

  3.x²-xy+yz-xz

  4.6x²+5x-4

  5.2a²-7ab+6b²

  6.(x²-2x)²+2(x²-2x)+1

  7.(x²-2x)²-14(x²-2x)-15

  8.x²(x-y)+(y-x)

  9.169(a+b)²-121(a-b)²

  10.(x-3)(x-5)+1

  答案:1.(2a-b)²+8ab=(2a+b)²

  2.y²-2y-x²+1=(y-1)²-x²=(y-1-x)(y-1+x)

  3.x²-xy+yz-xz=x(x-y)-z(x-y)=(x-z)(x-y)

  4.6x²+5x-4=(2x-1)(3x+4)

  5.2a²-7ab+6b²=(2a-3b)(a-2b)

  6.(x²-2x)²+2(x²-2x)+1=(x²-2x+1)²=(x-1)^4

  7.(x²-2x)²-14(x²-2x)-15=(x²-2x-15)(x²-2x+1)=(x+3)(x-5)(x-1)²

  8.x²(x-y)+(y-x)=(x²-1)(x-y)=(x+1)(x-1)(x-y)

  9.169(a+b)²-121(a-b)²

  =(14a+14b-11a+11b)(14a+14b+11a-11b)

  =(3a+25b)(25a+3b)

  10.(x-3)(x-5)+1=(x-3)²-2(x-3)+1=(x-3-1)²=(x-4)²

  -5a^2+16a=a(16-5a)

  8x^2-4x=4x(2x-1)

  15p+10p^2=5p(3+2p)

  -3x^2y-6xy=-3xy(x+2y)

  14m^3n^2-6m^2n^3=2m^2n^2(7m-6n)

  27a^2b^3c+18ab^2=9ab^2(3abc+2)

  18xy^2z^3+12x^2y^2

2019-03-18 12:55:07

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