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# 书 山 有 路 勤 为 径，学 海 无 崖 法 作 舟 - PowerPoint PPT Presentation

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## PowerPoint Slideshow about ' 书 山 有 路 勤 为 径，学 海 无 崖 法 作 舟' - ezra-james

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(a+b)(a-b)=a2-b2，

(a±b)=a2±2ab+b2，

(2)(-2x-y)(2x-y)．

(1)19982-1998·3994+19972；

(2+1)(22+1)(24+1)(28+1)+1．

=(22-1)(22+1)(24+1)(28+1)+1

=…

=216．

(2x-3y-1)(-2x-3y+5)

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

=(2-3y)2-(2x-3)2=9y2-4x2+12x-12y-5．

∴ 2a2+2b2=2[(a+b)2-2ab]

=2(92-2·14)=106，

(2x+y-z+5)(2x-y+z+5)．

=(2x+5)2-(y-z)2

=4x2+20x+25-y2+2yz-z2

1. │5x-2y│·│2y-5x│的结果是[ ]

A.(5x-2y)2 B.-(5x-2y)2

C.-(2y-5x)2 D.(5x)-(2y)2

2. 已知x+y=10, xy=24,则x2+y2的值是[ ]

A.52 B.148 C.58 D.76

3. 若a-b=2 , a-c=1 则(2a-b-c)2+(c-a)2的值是[ ]

A.9 B.10 C.2 D.1

4. 已知(a+b)2=11, (a-b)2=7则2ab为[ ]

A.2 B.-1 C.1 D.-2

[ ]

A.9 B.11 C.23 D.1

1. (x-1)2(x+1)2(x2+1)2=________．

2. 解方程

3(x-1)2-3x(x-5)=21

3. 解方程

5.利用公式进行计算：

(1)(2x+y-z+5)·(2x-y+z+5)；

(2)(a+b)2+(a-b)2+(-2a-b)(2a+b)；

1. 计算：

(2x+y-z+5)(2x-y+z+5)．

=[(2x+5) +(y-z)] [(2x+5) -(y-z)]

=(2x+5)2-(y-z)2=4x2+20x+25-y2+2yz-z2

2.

xy=x+y

3. 先化简，后求值:3x(-4x3y2)2-(2x2y)3·5xy 其中 x=1, y=2 .

4. 己知x+5y=6 , 求 x2+5xy+30y 的值。

5.解方程：(2x-3)2 = (x-3)(4x+2)

6.解不等式：(3x+4)(3x-5)<9(x-2)(x+3)

9.己知 2x-3y=-4 , 求代数式4x2+24y-9y2的值。

• 当x=-1 ,y=-2 时，求代数式
• [2x2-(x+y)(x-y)][(-x-y)(-x+y)+2y2]的值.

15.用科学记数法表示：0.0000000461

16.己知x+y=4 , 求 x3+12xy+y3的值。

13. 计算：(a-1)(a4+1)(a2+1)(a+1)

14. 计算：(2a-b)2(b+2a)2

17. 己知x+y=3 ，x2+y2=5 则xy 的值等于多少？

18. 己知x-y=4 , xy=21 ,则 x2+y2的值等于多少？

19. 根据己知条件，确定m ,n 的值

(a)己知：25m·2·10n=57·24

(b)己知: (x+1)(x2+mx+n) 的计算结果不含x2和x项。

B

·

A

C