八年级因式分解题目，求大神
\u516b\u5e74\u7ea7\u56e0\u5f0f\u5206\u89e3\u9898x²\uff08a-1\uff09+y²\uff081-a\uff09=x²\uff08a-1\uff09-y²\uff08a-1\uff09=(x²-y²)\uff081-a\uff09=(x+y)(x-y)(1-a)
-x³+x²-1/4x=x(-x²+x-1/4)=-1/4(4x²-4x+1)=-1/4(2x-1)^2
\uff08m²+n²\uff09²-4m²n²=m^4+n^4+2m²n²-4m²n²=m^4+n^4-2m²n²=\uff08m²-n²\uff09²=[\uff08m+n\uff09(m-n)]²
\uff08a+3b\uff09²-\uff083a+b\uff09²=a^2+9b^2+6ab-9a^2-b^2-6ab=8b^2-8a^2=8(b-a)(b+a)
x^4-2x²y²+y^4=(x^2-y^2)^2=[(x+y)(x-y)]^2
x²\uff08a-2\uff09+4y²\uff082-a\uff09=x²\uff08a-2\uff09-4y²\uff08a-2\uff09=(x²-4y²)\uff08a-2\uff09=(x+2y)(x-2y)(a-2)
\uff085m²+3n²\uff09²-\uff083m²+5n²\uff09²=25m^4+9n^4+30m^2n^2-9m^4-25n^4-30m^2n^2=16m^4-16n^4=16(m^2+n^2)(m^2-n^2)=16(m^2+n^2)(m+n)(m-n)
3a²-1/3b²=1/3(9a^2-b^2)=1/3(3a+b)(3a-b)
9\uff08a+b)^2-4(a-b)^2
=[3\uff08a+b)]^2-[2(a-b)]^2
=[3\uff08a+b)+2(a-b)][3\uff08a+b)-2(a-b)]
=(5a+b)(a+5b)
5x²-20 = 5(x²-4) = 5(x+2)(x-2)
15题：
9x²-6x+1=(3x-1)²；或9x²+6x+1=(3x+1)²
16题：
ax²+bx+1 与 2x²-3x+1的积 不含3次项和1次项，即：
-ax²*3x+bx²*2x=0；bx*1-1*3x=0
-3a+2b=0；b-3=0
a=2，b=3
17题：
(a+b)^4 = a^4 + 4a^3b + 6a^2b^2 + 4ab^3 + b^4
18题：
(1-1/2^2)(1-1/3^2)(1-1/4^2)......(1-1/9^2)(1-1/10^2)
= (1-1/2)(1+1/2)(1-1/3)(1+1/3)......(1-1/9)(1+1/9)(1-1/10)(1+1/10)
= 1/2 * 3/2 * 2/3 * 4/3 *.......* 8/9 * 10/9 * 9/10 * 11/10
= 1/2 * 11/10
= 11/20
19题：
[ 5xy^2 (x^2-3xy) - (-3x^2y^3)^3 ] ÷ 5xy^2
= 5xy^2 (x^2-3xy) ÷ 5xy^2 - (-3x^2y^3)^3 ÷ 5xy^2
= (x^2-3xy) + 27x^6y^9 ÷ 5xy^2
= x^2 - 3xy+ (27/5)x^5y^7
a(a-2b)-(a-b)^2
= a^2 - 2ab - (a^2-2ab+b^2)
= a^2 - 2ab - a^2+ 2ab-b^2
= -b^2
一题一帖！
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绛旓細鍥犲紡鍒嗚В3a3b2c锛6a2b2c2锛9ab2c3锛 3.鍥犲紡鍒嗚Вxy锛6锛2x锛3y锛 4.鍥犲紡鍒嗚Вx2(x锛峺)锛媦2(y锛峹)锛 5.鍥犲紡鍒嗚В2x2锛(a锛2b)x锛峚b锛 6.鍥犲紡鍒嗚Вa4锛9a2b2锛 7.鑻ュ凡鐭3锛3x2锛4鍚湁x锛1鐨勫洜寮忥紝璇曞垎瑙3锛3x2锛4锛 8.鍥犲紡鍒嗚Вab(x2锛峺2)锛媥y(a2锛峛2)锛 9.鍥犲紡鍒嗚В(x锛媦...
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绛旓細1.(x+y)²-4锛坸+y-1)=(x+y)²-4(x+y)+4 =(x+y)²-2脳2(x+y)+2²=(x+y-2)²2.(x-y)²+4xy =x²-2xy+y²+4xy =x²+2xy+y²=(x+y)²3.(x-1)(x+3)+1 =x²+2x+1-3 =(x+1)²-3...
绛旓細2.宸茬煡2x-y=1/3,xy=2,姹2x^4y^3-x^3y^4鐨勫 2x^4y^3-x^3y^4 =(xy)^3(2x-y)=2^3*1/3 =8/3 3.鑻4x^2-4x+9y^2-12y+5=0,姹6x+2/3y鐨勫 4x^2-4x+9y^2-12y+5=0 (4x^2-4x+1)+(9y^2-12y+4)=0 (2x-1)^2+(3y-2)^2=0 涓婂紡鎴愮珛蹇呴』鏈2x-1=0,x=1...
绛旓細x6-x5+x4+x3+1 a2-8ab+16b2+6a-24b+9=(a-4b)²+6(a-4b)+9=(a-4b+3)²(x+2y)(3x-7y)2-4(x+2y)(x+y)2=(x+2y)(3x-7y+2x+2y)(3x-7y-2x-2y)=5(x+2y)(x-y)(x-9y)(a+2b)3+(a-2b)3=(a+2b+a-2b)[(a+2b)²-(a+2b)(a-2b)+锛坅-2b...
绛旓細-[3(x-y)]²=(5x+5y+3x-3y)(5x+5y-3x+3y)=(8x+2y)(2x+8y)=8(4x+y)(x+4y)闂琛ュ厖锛氳繕鏈変竴涓 鍏鍒嗚В鍥犲紡锛鍐嶈绠 蟺R1^2+蟺R2^2+蟺R3^2,鍏朵腑R1=4 R2=8 R3=10 蟺鍙3.14 蟺R1^2+蟺R2^2+蟺R3^2 =蟺(R1^2+R2^2+R3^2)=3.14(16+64+100)=565.2 ...
绛旓細2)銆佺敤鍗佸瓧鐩镐箻娉曡В涓浜涙瘮杈冮毦鐨棰樼洰 渚5鎶14x²-67xy+18y²鍒嗚В鍥犲紡 鍒嗘瀽锛氭妸14x²-67xy+18y²鐪嬫垚鏄竴涓叧浜巟鐨勪簩娆′笁椤瑰紡,鍒14鍙垎涓1脳14,2脳7, 18y²鍙垎涓簓.18y , 2y.9y , 3y.6y 瑙: 鍥犱负 2 -9y 7 鈺 -2y 鎵浠 14x²-67xy+18y&...
绛旓細1.(1)=[2(x²+6x+1)+(x²+1)][(x²+6x+1)+2(x²+1)]=(2x²+12x+2+x²+1)(x²+6x+1+2x²+2)=(3x²+12x+3)(3x²+6x+3)=9(x²+4x+1)(x+1)²(2)=(x²+8x+7)(x²+8x+15)+15 ...
