(1)x=6,则x=(2)x=(-4),则x= (3)多项式x+mx+64是完全平方式,则m= (4)若a+b=4,ab

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  • (1)∵X^3=6^3 ∴X=6 ; (2)∵X^3=(-4)^3 ∴X=-4 ;(3)∵X^2+MX+64是完全平方式,∴X^2+MX+64=(X+8)^2=X^2+16X+64 即M=16;(4)依题得a^2+b^2=(a+b)^2-2ab=4^2-2*3=10; (5)x^2y^2-y^2=(XY-Y)(XY+Y)=Y^2(X-1)(X+1); (7)1/2(2X-1)^3=-4 化简得(2X-1)^3=(-2)^3 ∴2X-1=-2 X=-1/2 (8)(-2x)*(-3xy)=(-2)^3*(-3)^2X^6X^4Y^6=-72X^10Y^6 (9)(2x+3)(x-4)-(x+2)(x-3)=(2X^2-8X+3x-12)-(x^2-3x+2x-6)=x^2-4x-6 (10)(2x-3y+1)(2x+3y-1)=〔2X-(3Y-1)〕〔2X+(3Y-1)〕=4X^2-(3Y-1)^2=4X^2-9Y^2+6Y-1 (11)(a-2b)-(3a-b)(3a+b)=A^2-4AB+4B^2-(9A^2-B^2)=-8A^2-4AB+5B^2 (12)∵4a(a+1)-(2a+1)(2a-1)=4a^2+4a-(4a^2-1)=4a+1∵a=-3/4 即这个式子的值为4×(-3/.4)+1=-2 (13)2m-18m=2m(1-9m^2)=2m(1-3m)(1+3m) (14)(2x-y)-25x=(2x-y-5x)(2x-y+5x)=(-3x-y)(7x-y)