已知x1和x2是方程x²+3x+1=0的两个实数根,则x1³+8 x2+20=?详细过程谢谢最好写在纸上,清楚一点
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![已知x1和x2是方程x²+3x+1=0的两个实数根,则x1³+8 x2+20=?详细过程谢谢最好写在纸上,清楚一点](/uploads/image/z/963164-20-4.jpg?t=%E5%B7%B2%E7%9F%A5x1%E5%92%8Cx2%E6%98%AF%E6%96%B9%E7%A8%8Bx%26%23178%3B%2B3x%2B1%3D0%E7%9A%84%E4%B8%A4%E4%B8%AA%E5%AE%9E%E6%95%B0%E6%A0%B9%2C%E5%88%99x1%26%23179%3B%2B8+x2%2B20%3D%3F%E8%AF%A6%E7%BB%86%E8%BF%87%E7%A8%8B%E8%B0%A2%E8%B0%A2%E6%9C%80%E5%A5%BD%E5%86%99%E5%9C%A8%E7%BA%B8%E4%B8%8A%EF%BC%8C%E6%B8%85%E6%A5%9A%E4%B8%80%E7%82%B9)
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已知x1和x2是方程x²+3x+1=0的两个实数根,则x1³+8 x2+20=?详细过程谢谢最好写在纸上,清楚一点
已知x1和x2是方程x²+3x+1=0的两个实数根,则x1³+8 x2+20=?
详细过程谢谢
最好写在纸上,清楚一点
已知x1和x2是方程x²+3x+1=0的两个实数根,则x1³+8 x2+20=?详细过程谢谢最好写在纸上,清楚一点
x1和x2是方程x²+3x+1=0的两个实数根
∴x1²+3x1+1=0,x1+x2=-3
即 x1²=-1-3x1
x1³+8 x2+20
=x1×x1²+8x2+20
=x1×(-1-3x1)+8x2+20
=-x1-3x1²+8x2+20
=-x1-3×(-1-3x1)+8x2+20
=8x1+8x2+3+20
=8*x1+x2)+23
=8×(-3)+23
=-1