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??1??1?????3x??a?2??b? ???3x+2??3x-2?=?3x?2 - 22 ?a + b??a - b? = a2-b2
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?b+2a??2a-b?=?2a+b??2a-b??
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(1) (a+3b)(a-3b)=(2) (3+2a)(-3+2a)= ?3??-a-b??a-b?=?4??a5-b2??a5+b2?= ?5??a - b??a+b??a2+b2?=(6) 51 49 =
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?1??2??3??4??5??6??7?
2
?xy+1??xy-1?= (2a-3b)(3b+2a)=(-2b-5)(2b-5) =( x-y)( x+y)=
(3x+4)(3x-4)-(2x+3)(2x-2) 998 1002 = 2001 1999 =
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2.152???????________________=____________________
3.????152??1,????:_________________ . ????,??
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2?,(1)102=______,98=_______???????
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5. ??153?????.
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1 . ?????????????ה.
(1)(a-b)(a+b)=a2-b2??? (2)(b+a)(a-b)=a2-b2?? ?
(3)(b+a)(-b+a)=a2-b2;? ?(4)(b-a)(a+b)=a2-b2?? ?
(5)(a-b)(a-b)=a2-b2. ? ?
2.????????????? ?
A (2a-3b)(-2a+3b) B (-3a+4b)(-4b-3a)
C (a-b)(b-a) D (a-b-c)(-a+b+c)
3.?????????
(1) (a+3b)(a-3b) (2) (3m-4n)(4n+3m)
(3) (3b+a)(a-3b) (4) (7-2a)(-7-2a)
(5) 20011999 (6) 9981002
?7? (y+3)(y-3)-(y-4)(y+5)?8??a-b??a+b??a2+b2?
4.a-b=20,?a+b= -5, ??
5.???????n????(n+3)(n-3)-(n+2)(n-2)????????????????
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2???(???)___________________________,_________________
4. 155????????__________________________________
5.??155?????.
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1.???????????????????????? ?
?(a+b)(a-b)= ??????? ??.
2. ????????? ?
A (a-b)2=a2-b2B (a+2b)2=a2+2ab+4b2?;
C (-m-n)2=m2+2mn+n2? D (a2+b)2=a4+2a+1?
3.???????????
(1) (x+6)2(2) (-m-2)2(3) (-2x+5)2 (4) (x-y)2
4332
(5) [(a-b)2 -(a+b)2 ] 2
4. (x-2y)2=(x+2y)2=m.?m????
A 4xy;B -4xy;C 8xy;D -8xy
5.??16x2+kx+1????????k?? ?
6. ??x-y=9?xy=8,?x2+y2???.
7.?????
(3x+2y)(3x-2y)-(3x+2y)2+(3x-2y)2 ??x=3,y=2
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(1)(a+b)-c (2)-(a-b)+c (3)a+(b-c)
(4)a-(b+c) (5)a+2(b-c) (6)a-3(b+c)
(7)4(a+b)-c (8)-5(a-b)+c
2?????155???????????????????
(1) a+b-c= ?_______?-c(2) a+b-c= -?_______?
-c
(3) a-b-c= ?_______?-c (4) -a+b-c= -?_______?
-c
3. ????155??5,?????,
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发表于 2019-9-13 23:46:11