1、第18課: 多項式乘法公式 2022-5-322.2.利用完全平方公式計算利用完全平方公式計算: :（1 1）1021022 2 ；（；（2 2）1971972 2 . .22200920092008220083）（，若14. 3abba.22的值求ba (1) (2a3)2 (2a+ 3)21.用乘法公式計算：用乘法公式計算：(2) (2a3)2 (a+1) (a1) ;(3) x(x+1)(x+3) (x3);(4) (2xy)(2x+y)(x+2y) (x+2y);2022-5-333.3.先化簡再求值先化簡再求值: : 3(x-1) 3(x-1)2 2-5(x+1)(x-1)+2(x+

2、1)-5(x+1)(x-1)+2(x+1)2 2 , ,其中其中x=-3,x=-3,(2)(x+3)(x-2)-(x-5)(2)(x+3)(x-2)-(x-5)2 2 ; ;1.1.計算計算: :答案答案 -6-6 (1)(x+3)(1)(x+3)2 2-(x+2)(x-1)-(x+2)(x-1) ; ;（3 3）(2x+3)(3x-2)-6(x-1)(2x+3)(3x-2)-6(x-1)2 2 -17x-17x2.2.已知已知x x2 2=3,=3,求求x(x+3)x(x+3)2 2-x(x-1)-x(x-1)2 2-2(4x+1)-2(4x+1)的值的值答案答案 8x8x2 2-2-2 (

3、4) (a+b-3)(a+b+3)(4) (a+b-3)(a+b+3)2022-5-34 3-122x xxx（ ）、（）(1)、2x(x+1)+3x(2x-5) 22132x xxx（ ）、 1.化簡化簡(4) (a+3b) (a- -3b) - -(a+b) (a- -b) (5) (a- -1)2 - -(a+3) (a- -3) (6) (-x-y)(-x+y)- (-x-y)(-x-y)(-x+y)- (-x-y)2 22022-5-35(1)、2x(x-1)-x(2x-3) 1.化簡化簡(2) (-a-2b) (a- -2b) - -(a+2b)2 +4ab(3) (a-3-3)2

4、 - -(a+3) (a- -1) +8a(4) (x-y)(x+y)- (-x-y)(x-y)(x+y)- (-x-y)2 2+2y+2y2 225)(31)(61- (5)baba、(6) 12(x-y)(x-y)3 3 4(x-y)(x-y)(7) (a+b) (a- -b)- -(a+b)2(4a2b-2ab2)2b2022-5-36 1.化簡化簡(1) (a-2b) (a+2b) - -(a+2b)2 +4ab 【答案答案-8b2(2) (a-b)(a+b)- (a-b)(a-b)(a+b)- (a-b)2 2+2b+2b2 2 答案答案2ab2ab26)(21)(141- (5)b

5、aba、(6) 15(x-y)(x-y)3 3 3(x-y)(x-y)(3) (-a+b) (a+b)- -(a+b)2(4a2b-4ab2)2b 【答案答案0】(4) (a+b-5)(a+b+5)(4) (a+b-5)(a+b+5)2022-5-37 1.化簡化簡(4) (a-2b) (a+2b) - -(a+2b)2 +8b2 答案答案4ab(5) (a-2-2)2 - -(a+5) (a- -1) -5 【答案答案-8a】(6) (x-y)(x-y)(x-y)(x-y)2 2 (x-y)(x-y)2 2(x y)y)3 3 答案（答案（x-y)x-y)4 4 )( (7)24bababa（、(8) 15(x-y)(x-y)6 6 5(x-y)(x-y)2 2(3) 9 3n 3n1 (1) (a2 a3) ( a4 a1 ) (2) a2a3+ a6a+a5 2022-5-38 1.化簡化簡 (4) (a+3b)2 - - (a+3b) (a- -3b) )- - 18b2 (5) (a-3-3)2 - -(a+1) (a- -2) -11-11(6) (x-y) (x-y) 3 3(x-y)(x-y)2 2 (x-y)(x-y)(x y)y)4 4)( (7)23bababa（、(8) 12(x-y)