morfengmei
幼苗
共回答了967个问题 举报
∫[0,3]√(9-x^2)dx
=x√(9-x^2)|[0,3]+∫[0,3]x^2dx/√(9-x^2)
=∫[0,3] 9dx/√(9-x^2)-∫[0,3]√(9-x^2)dx
2∫[0,3]√(9-x^2)dx =9∫[0,3]d(x/3)/√[1-(x/3)^2]
∫[0,3]√(9-x^2)dx=(9/2)∫d(x/3)/√(1-(x/3)^2)
=(9/2)arcsin(x/3)|[0,3]
=(9/2)(π/2)
1年前
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