数学：第九章从面积到乘法公式复习课件(苏科版七年级下)

第九章从面积到乘法公式填空:1.(2x-y)(_____)=4x2-y22.(b-a)(_____)=a2-b23.4x2-12xy+(____)=(______)24.(-3x-2)(_____)=4-9x22x+y-a-b9y22x-3y-2+3x选择:在下列多项式的乘法中,能用平方差公式计算的是()A(a+3)(3+a)B(6x-y)(y+6x)C(-m+2n)(m-2n)D(a2-b)(a+b2)B下列各式是不是完全平方式？（1）a2-4a+4()(2)a2+4a+16()(3)a2-8a+16()(4)a2-6a+9()(5)a2+()√×√√21124abb×选择:小兵计算一个二项整式的平方式时,得到正确结果是4x2++25y2,但中间一项不慎被污染了,这一项应是()A10xyB20xyC±10xyD±20xyD(1)26n32nn3n2.(xy)+3(-xy)+2(-xy)518(2).(0.125)2223322(3).(0.6ab)×5ab-(-0.3ab)×(5ab)2n6n2n6n2n6n解:原式=xy+3xy+2xy2n6n=6xy82212)21(:18151853原式解5555552433243.95.78.1253.0536.0:babababaababba原式解计算:23222(4).3x(xy-2x)-4x(-xy)2(5).(1)(5)ttt(6).(23)(45)(23)(54)xyxyxyyx325253256463:xyxyxxyx原式解5454)54(:2222ttttttt原式解4224222222524464)1625)(94(:yyxxxyyx原式解222(7).(1)(1)(1)(1)xxxx(8).(46)(46)xyzxyz22222(9).(3)(3)(3)xxx2222222222)11)(1()1()1)(1(:xxxxxxx原式解22222364816)64()]64()][64([:zyzyxzyxzyxzyx原式解222222222222222222236)33)(33()3()3()]3)(3[()3(:xxxxxxxxxx原式解(10)(a-1)(a4+1)(a2+1)(a+1)(11)(2a-b)2(b+2a)211)()1)(1()1)(1)(1(82444422aaaaaaa原式解42242222816]4[)]2)(2[(bbaabababa原式解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。36)5(630630)5(65:yxyxyyxxyx原式解5.解方程：(2x-3)2=(x-3)(4x+2)217215152612249124:22xxxxxxx解22116.:1,.aaaa己知求的值44117.5,.xxxx己知求的值8.己知2x-3y=-4,求代数式4x2+24y-9y2的值。9.当x=-1,y=-2时，求代数式[2x2-(x+y)(x-y)][(-x-y)(-x+y)+2y2]的值.16)4(4)32(424)32(424)32)(32(432yxyyxyyxyxyx原式解25])2()1[()())((]2)][(2[2222222222222222yxyxyxyyxyxx原式解13.己知x+y=3，x2+y2=5则xy的值等于多少？14.己知x-y=4,xy=21,则x2+y2的值等于多少？2459)(92929)(532222222xyyxxyyxyxyxyxyx故即解582121621616216)(21422222xyyxyxyxyxxyyx即解15.己知:(x+1)(x2+mx+n)的计算结果不含x2和x项。求m,n的值.32232(1)()10101xmxnxxmxnxmxmnxnmmmnn解原式16.把下列各式分解因式：(1)x4-18x2+81(2)16x4-72x2y2+81y4(3)(x2+y2)2-4x2y2(4)(a2+4)2-16a21.-ab(a-b)2+a(b-a)22.16a2b-16a3-4ab23.(2x+y)2-(x+2y)24.(x2+4x)2+8(x2+4x)+1617.把下列各式分解因式：1x2+2x3=2x22,2x3+3x4=2x32,3x4+4x5=2x52……你能发现什么规律吗?探索研究探索研究将这个图形剪开并拼成一个长方形或一个梯形,推出平方差公式.aaa-bbba-b