化简(1)(2)(3)(4)

化简1/2!+2/3!+3/4!+...+(n-1)/n! 化简,计算1.化简.(1) -(+7) (2) -[-(-3)] (3) -|+[-(-200]| (4) +[-(-1 [(a+1)^3]^4*(a+1)^2化简 化简：(1/3a-3/4b)^2-(1/3a+3/4b)^2 4分之1比3分之2化简 化简 (3+1)(3^2+1)(3^4+1)(3^6+1) [(1-a^2)^(1/4)+(a^2-1)^(1/2)+3a]/(1-a)化简 2√1/3化简 化简：1/(n+1)(n+2)+1/(n+2)(n+3)+1/(n+3)(n+4) 化简：1/(x+1)(x+2)+1/(x+2)(x+3)+1/(x+3)(x+4) 化简-[(4^-2)(xy^-1)(z/-3)]^2/[(-2x)^2(yz)^4]^-2 化简3x^2(x-1)-3x(x^2+1)+4x(2X-5)