①(x²-2x)(2x²-2x-2)-3②(x²+2x)(x²+4x+3)+1③(x+1)(x+2)(x+3)(x+6)+x²

①(x²-2x)(2x²-2x-2)-3②(x²+2x)(x²+4x+3)+1③(x+1)(x+2)(x+3)(x+6)+x²
①(x²-2x)(2x²-2x-2)-3
②(x²+2x)(x²+4x+3)+1
③(x+1)(x+2)(x+3)(x+6)+x²

①(x²-2x)(2x²-2x-2)-3②(x²+2x)(x²+4x+3)+1③(x+1)(x+2)(x+3)(x+6)+x²
①令 t = x^2-2x ∴原式 = t^2 - 2t - 3 =(t-3)(t+1) =(x-3)(x+1)(x-1)^2
②令 t = x^2+3x
原式 = x(x+2)(x+1)(x+3)+1 = (x^2+3x)(x^2+3x+2)+1 = t^2+2t+1 = (t+1)^2 = (x^2+3x+1)^2
③ 令 t = x^2 +6x
原式 = x^4+12x^3+48x^2+72x+36 = (x^2 + 6x)(x^2 + 6x +12) +36 = t^2+12t +36
=(t+6)^2 = (x^2+6x+6)^2
或者 令t=x^2+6
原式 = (7x+t)(5x+t)+x^2 = 35x^2 + 12xt +t^2 +x^2 = 36x^2 + 12xt + t^2
= (6x+t)^2 = (x^2 + 6x +6)^2

1) 2x^4-2x^3-2x^2-4x^3+4x^2+4x-3
=2x^4-6x^3+2x^2+4x+3
2)x^4+4x^3+3x^2+2x^3+8x^2+6x+1
=x^4+6x^3+11x^2+6x+1
3)(x^2+3x+2)(x^2+9x+18)+x^2
=x^4+9x^3+18x^2+3x^3+27x^2+54x+2x^2+18x+36+x^2
=x^4+12x^3+48x^2+72x+36

1.利用分解因式进行计算 0.746×136+0.54×13.6+27.2 2.若m-n=-21 7.46*13.6+0.54*13.6+2*13.6=13.6*(7.46+0.54+2)=13.6