1.(2x+3y)(3x-y)=___6x2+7xy-3y2_____ 2.(2x-3y)(3x-2y)=____6x2-13xy+6y2_____ 3.(4x+6y)(2x-3y)=__8x2-18y2___ 4.(2x-1)2-(x+2)2=___4x2-4x+1-x2-4x-4=3x2-8x-3___ 5.(2x+__y__)(__2x__-y)=4x2-y2 6.(1+x)(1-x)(1+x2)(1+x^4)=__1-x^8__ 7.(2x+5y-3)(-2x+5y+5)=__-4x2+25y2+20x+50y-15____ 8.(x+y)2(x-y)2=___x^4-2x2y2+y^4___ 9.(a-1/2)2(a2+1/4)2(a+1/2)2=_a^8-a^4/8+1/256___ 10.(a-2b+c)(a+2b-c)-(a+2b+c)2= =a2-(2b-c)2-a2-2a(2b+c)-(2b+c)2 =-4b2+4bc-c2-4ab-2ac-4b2-4bc-c2 =-8b2-2c2-4ab-2ac (2x-1)(x+2)-(x-2)2-(x+2)2,其中x=负的1又二分之一 =2x2+3x-2-x2+4x-4-x2-4x-4 =3x-10 =-3/2+10 =17/2
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