分类：教育/科学-升学入学-高考
问题：求不定积分∫（x+1)/(x^2
∫（x+1)/(x^2-x+1) dx
回答：解：由于(x^2-x+1)`=2x-1=2(x+1)-3
所以x+1=(1/2)[(2x-1)+3]，故
∫[(x+1)/(x^2-x+1)]dx
=(1/2)∫[(2x-1)+3]dx/(x^2-x+1)
=(1/2)∫(2x-1)dx/(x^2-x+1)+(3/2)∫dx/(x^2-x+1)
=(1/2)∫(x^2-x+1)`dx/(x^2-x+1)+(3/2)∫dx/[(x-1/2)^2+3/4]
=(1/2)∫d(x^2-x+1)/(x^2-x+1)
+(3/2)∫d(x-1/2)/[(x-1/2)^2+(√3/2)^2]
=(1/2)ln|x^2-x+1|+[(3/2)/(√3/2)]arctan[(x-1/2)/(√3/2)]+C
=(1/2)ln(x^2-x+1)+√3arctan[(2x-1)/√3]+C