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=x 2 +5 x +6 =x 2 -3 x -4 =x 2 -11 x + 30

活动与探索： ① ( x +2)( x +3) ②( x -4)( x +1) ③ ( x -5)( x -6) ( x + p )( x + q ). =x 2 +5 x +6 =x 2 -3 x -4 =x 2 -11 x + 30. =x 2 +( p + q ) x + pq. 利用你发现的规律口答： ① ( y +4 )( y -2 ) ②( y -5 )( y -3 ) ③( a -2 )( a +5 ) ④( a +9 )( a -9 ). 口答 : (1)(P+1) 2 ＝ (P+1)(P+1 )= . (2)(m+2) 2 = .

melanie-whitney
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=x 2 +5 x +6 =x 2 -3 x -4 =x 2 -11 x + 30

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  1. 活动与探索： ①(x+2)(x+3) ②(x-4)(x+1) ③ (x-5)(x-6) (x+p)(x+q) =x2+5x+6 =x2-3x-4 =x2-11x+30 =x2+(p+q)x+pq

  2. 利用你发现的规律口答： ①(y+4)(y-2) ②(y-5)(y-3) ③(a-2)(a+5) ④(a+9)(a-9)

  3. 口答: (1)(P+1)2＝(P+1)(P+1 )=. (2)(m+2)2=. (3) (P-1)2＝(P-1)(P-1)=. (4)(m-2)2 =. p2+2p+1 m2+4m+4 p2-2p+1 m2-4m+4

  4. 完全平方公式

  5. (a+b)2= a2 +2ab+b2 (a-b)2= a2- 2ab+b2 完全平方公式： 两个数的和（或差）的平方，等于它们的平方和，加上（或减去）它们的积的2倍。

  6. 练一练 ①(x+6)2 ②(y-5)2 ③(-2x+5)2 ④(3x-7y)2 ⑥(2a2+3b)2 ⑦(4a2 - b2 )2 3 2 ⑤( 2 y ) x - 3 4 1 ⑧( - 2 2 x 2 y ) 2

  7. 想一想： ①29×31×(302+1) ②8.92 ③1992

  8. 探究: 如果x2+mx+4是一个完全平方式,求m的值.

  9. 你会了吗？ 1、若a2+mab+b2是一个完全平方式,则m=______ 2、若x2+mxy+9y2是一个完全平方式,则m=______ 3、若4x2+mxy+9y2是一个完全平方式,则m=______

  10. 思考： (a+b)2与(-a-b)2相等吗？ (a-b)2与(b-a)2相等吗？ (a-b)2与a2-b2相等吗？

  11. 你会了吗？ ①(-x-y)2 ②(-2a2+b)2

  12. 能力提升： 1、若a+b=5且ab=12,则 a2+b2=____ 2、若a2+b2=25且ab=12,则a+b=_____ 3、若 a2+b2+4a-6b+13=0求ab的值

  13. 通过这节课的学习 你学到了什么

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