解方程：（1）2x^4+3x^3-x^2+2x+3=0 （2）2x^4-7x^3+9x^2-7x+2=0
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（2）可以分解因式：2x^4-7x^3+9x^2-7x+2=(-2 + x) (-1 + 2 x) (1 - x + x^2)。根为：2，1/2，1/2-Sqrt[3]/2，1/2+Sqrt[3]/2。
（1）无法像（2）有一个较好的分解，有四次方程的求根公式，但超级复杂，用mathematica、matlab等可以求得（1）有两实根两虚根，很复杂……大约为： -1.82727，-0.8082，0.567737 - 0.832696 i，0.567737 + 0.832696 i。精确值：
-(3/8) + 1/2 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)] - 1/2 Sqrt[43/24 - 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) - 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3) - 115/(32 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)])]
-(3/8) + 1/2 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)] + 1/2 Sqrt[43/24 - 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) - 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3) - 115/(32 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)])]
-(3/8) - 1/2 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)] - 1/2 Sqrt[43/24 - 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) - 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3) + 115/(32 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)])]
-(3/8) - 1/2 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)] + 1/2 Sqrt[43/24 - 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) - 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3) + 115/(32 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)])]
（1）无法像（2）有一个较好的分解，有四次方程的求根公式，但超级复杂，用mathematica、matlab等可以求得（1）有两实根两虚根，很复杂……大约为： -1.82727，-0.8082，0.567737 - 0.832696 i，0.567737 + 0.832696 i。精确值：
-(3/8) + 1/2 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)] - 1/2 Sqrt[43/24 - 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) - 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3) - 115/(32 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)])]
-(3/8) + 1/2 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)] + 1/2 Sqrt[43/24 - 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) - 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3) - 115/(32 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)])]
-(3/8) - 1/2 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)] - 1/2 Sqrt[43/24 - 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) - 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3) + 115/(32 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)])]
-(3/8) - 1/2 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)] + 1/2 Sqrt[43/24 - 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) - 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3) + 115/(32 Sqrt[43/48 + 1/6 (1429/2 - (3 Sqrt[152949])/2)^(1/3) + 1/6 (1/2 (1429 + 3 Sqrt[152949]))^(1/3)])]
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