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matlab中计算四次方方程a*x^4+b*x+c=0的实数根.

学习 时间:2026-03-31 21:32:28 阅读：2038
matlab中计算四次方方程a*x^4+b*x+c=0的实数根.我是想计算a*x^4+b*x+c=0的x根,但是a、b、c是需要计算的,我想问下在matlab里如何计算呢?我只要那个正实数根,其他的都不要.在百度上看到你回答类似的问题,但是不是很明白.
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最佳回答

愉快的向日葵

优秀的金毛

2026-03-31 21:32:28

syms a x b c
y = a*x^4+b*x+c;
Y = solve(y, 'x')
结果如下：
ans =

1/12*6^(1/2)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)+1/12*(-(6*12^(1/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+24*12^(2/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*c*a+72*b*6^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3)/(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2))^(1/2)
1/12*6^(1/2)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)-1/12*(-(6*12^(1/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+24*12^(2/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*c*a+72*b*6^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3)/(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2))^(1/2)
-1/12*6^(1/2)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)+1/12*(-(6*12^(1/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+24*12^(2/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*c*a-72*b*6^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3)/(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2))^(1/2)
-1/12*6^(1/2)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)-1/12*(-(6*12^(1/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+24*12^(2/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*c*a-72*b*6^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3)/(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2))^(1/2)

最新回答共有2条回答

  • 无私的纸鹤
    回复
    2026-03-31 21:32:28

    syms a x b cy = a*x^4+b*x+c;Y = solve(y, 'x')结果如下： ans = 1/12*6^(1/2)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)+1/12*(-(6*12^(1/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+24*12^(2/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*c*a+72*b*6^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3)/(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2))^(1/2) 1/12*6^(1/2)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)-1/12*(-(6*12^(1/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+24*12^(2/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*c*a+72*b*6^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3)/(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2))^(1/2) -1/12*6^(1/2)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)+1/12*(-(6*12^(1/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+24*12^(2/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*c*a-72*b*6^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3)/(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2))^(1/2) -1/12*6^(1/2)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)-1/12*(-(6*12^(1/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+24*12^(2/3)*(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2)*c*a-72*b*6^(1/2)*((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3)/(12^(1/3)*(((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(2/3)+4*c*12^(1/3)*a)/a/((9*b^2+(-768*c^3*a+81*b^4)^(1/2))*a)^(1/3))^(1/2))^(1/2)

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