1.-8×2^-1+根号2÷(tan30-cos45) =-8×(1/2)+√2÷(√3/3-√2/2)=-4+6√2/(2√3-3√2)=-4-6√2(3√2+2√3)/[(3√2)^2-(2√3)^2]=-4-(6+2√6)=-10-2√6因式分解 1.x^2-y^2-4x+4 =(x+y-2)(x-y-2)解方程 7x-1/2｛x-1/2...