三次方方程求解7x^3-18^2+5x-4=0没有看错

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三次方方程求解7x^3-18^2+5x-4=0没有看错

三次方方程求解7x^3-18^2+5x-4=0没有看错
三次方方程求解
7x^3-18^2+5x-4=0
没有看错

三次方方程求解7x^3-18^2+5x-4=0没有看错
7x^3-320+5x=0
7x^3+5x=320

x≈2.3719

x=2.3719把我选成最佳答案。谢谢了

solve('7*x^3-18*x^2+5*x-4=0')

ans =

[ 1/21*(5643+21*48390^(1/2))^(1/3)+73/7/(5643+21*48390^(1/2)...

全部展开

solve('7*x^3-18*x^2+5*x-4=0')

ans =

[ 1/21*(5643+21*48390^(1/2))^(1/3)+73/7/(5643+21*48390^(1/2))^(1/3)+6/7]
[ -1/42*(5643+21*48390^(1/2))^(1/3)-73/14/(5643+21*48390^(1/2))^(1/3)+6/7+1/2*i*3^(1/2)*(1/21*(5643+21*48390^(1/2))^(1/3)-73/7/(5643+21*48390^(1/2))^(1/3))]
[ -1/42*(5643+21*48390^(1/2))^(1/3)-73/14/(5643+21*48390^(1/2))^(1/3)+6/7-1/2*i*3^(1/2)*(1/21*(5643+21*48390^(1/2))^(1/3)-73/7/(5643+21*48390^(1/2))^(1/3))]

系数给错没有?应该没这么复杂吧?

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