作业帮 > 数学 > 作业

一道不定积分,∫[x^3/√(x^2+1)]dx

来源:学生作业帮 编辑:拍题作业网作业帮 分类:数学作业 时间:2024/05/01 17:21:57
一道不定积分,
∫[x^3/√(x^2+1)]dx
∫[x^3/√(x^2+1)]dx
=∫[x^2/√(x^2+1)]xdx
=1/2∫[x^2/√(x^2+1)]d(x^2+1)
=1/2∫*1/2*x^2d√(x^2+1)
=1/4∫x^2d√(x^2+1)
=1/4(x^2*√(x^2+1)-∫√(x^2+1)dx^2)
=1/4(x^2*√(x^2+1)-∫√(x^2+1)d(x^2+1))
=1/4(x^2*√(x^2+1)-3/2√(x^2+1)^3)+C
=1/4x^2*√(x^2+1)-3/8√(x^2+1)^3+C