(a+b)(a-b)=a^2-b^2 ä¾ï¼(5+2)ä¹ï¼5-2ï¼=5^2-2^2ã
(a+b)^2=a^2+2ab+b^2.(a-b)^2=a^2-2ab+b^2.
(-a-b)^2=a^2+2ab+b^2.(-a+b)^2=a^2-2ab+b^2.
ä¾:(5+2)=5^2+20+2^2.(-5-2)=5^2+20+2^2.
(5-2)=5^2-20+2^2.(-5+2)=5^2-20+2^2.
1.18.1ï¼ï¼3ï¼0.299÷0.23ï¼Ã1
2.(6.8-6.8Ã0.55)÷8.5
3.0.12à 4.8÷0.12Ã4.84
4.2Ã1.5+2.5÷(-1.6)
5.ï¼-2ï¼Ã3.2Ãï¼1.5+2.5ï¼Ã·1.6
6.6-1.6÷4+(6.8-9)
7.38+7.85-5.37÷89
8.7.2÷0.8-1.2Ã5
9.-1.19Ã3-0.43
10.6.5Ãï¼4.8-1.2Ã4ï¼
11.68Ã1.9+0.32Ã1.9
12.10.15-10.75Ã0.4-5.7
13.5.8Ãï¼3.87-0.13ï¼
14.(-8.01)+4.2Ã3.74
15.32.52-ï¼6+9.728÷3.2ï¼Ã2.5
16.[ï¼7.1-5.6ï¼Ã0.9-1.15] ÷2.5
17.5.4÷[2.6Ãï¼3.7-2.9ï¼+0.62]
18.12Ã6÷ï¼12-7.2ï¼-6
19.12Ã6÷7.2-6
20.33.02ï¼ï¼148.4ï¼90.85ï¼Ã·2.5
21.(-5)-252Ãï¼-78ï¼
22.(-6) Ã(-2)+3÷ï¼5+50ï¼
23.7-7+3-6-ï¼-90ï¼
24.(-8)(-3)Ã(-8)Ã25
25.(7+13) ÷(-616)÷(-28)
26.ï¼8+14-100-27ï¼Ã·4
27.(-15) ÷(-1)-101÷10
28.16÷0.21Ã(-8) Ã(4.1+5.9)
29.(-10) Ã(-2) Ã4÷{-9÷[6+(-5.67)]}
30.[-|98|+76+(-87)]*23[56+(-75)-(7)]-(8+4+3)
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2,(9x^2+2)(2x+1)
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4,(1/4-2/3y^2)(-1/4x-2/3y^2)
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2x-1/2-2x+5/3=6x-7/6-1
1.(2a+3b)*(2a-b)
2.(2x+y-1)çå¹³æ¹
解1.(2a+3b)*(2a-b) ç¨ååç¸ä¹æ³ å§
2 2 =4a2-3b2+4ab
3 -1
2.(2x+y-1)çå¹³æ¹ =4x2+y2+4xy +1-4x-2y
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ï¼5ï¼(â2a3b) (â6ab6c)
ï¼6ï¼ (2xy2) 3yx
ï¼1ï¼2abï¼5ab2+3a2bï¼
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(1) 3a3·5a3=15a3
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(2)
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(3)
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(3)
(4) ï¼3x(ï¼yï¼xyz)
(5) 3x2(ï¼yï¼xy2ï¼x2)
(6) 2ab(a2bï¼ c)
(7) (a+b2+c3)·ï¼ï¼2aï¼
(8) [ï¼(a2)3+(ab)2+3]·ï¼ab3ï¼
(9)
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2ãå·²ç¥æçæ°aãbãc满足 |aâbâ3|+ï¼b+1ï¼2+|cï¼1|=0ï¼
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