x^2-y^2-x+3y-2=(x^2-x+1/4)-(y^2-3y+9/4)=(x-1/2)^2-(y-3/2)^2=(x-1/2-y+3/2)(x-1/2+y-3/2)=(x-y+1)(x+y-2)
够详细吧,做这类题记住x和y分别凑平方,然后用平方差公式计算,祝好,满意请给分.