The first solution for a x 4 + b x 3 + c x 2 + d x + e {\displaystyle ax^{4}+bx^{3}+cx^{2}+dx+e} , as presented by Maxima (use "tex(solve(a*x^4 + b*x^3 + c*x^2 + d*x + e,x)[1])" and plug into the wiki)
x = − 2 − 3 2 − ( 18 a 2 ( − 256 a 3 e 3 − ( − 192 a 2 b d − 128 a 2 c 2 + 144 a b 2 c − 27 b 4 ) e 2 − ( ( 144 a 2 c − 6 a b 2 ) d 2 + ( 18 b 3 c − 80 a b c 2 ) d + 16 a c 4 − 4 b 2 c 3 ) e + 27 a 2 d 4 − ( 18 a b c − 4 b 3 ) d 3 − ( b 2 c 2 − 4 a c 3 ) d 2 6 3 a 3 − a ( 72 c e − 27 d 2 ) − 27 b 2 e + 9 b c d − 2 c 3 54 a 3 ) 2 3 + ( 24 a c − 9 b 2 ) ( − 256 a 3 e 3 − ( − 192 a 2 b d − 128 a 2 c 2 + 144 a b 2 c − 27 b 4 ) e 2 − ( ( 144 a 2 c − 6 a b 2 ) d 2 + ( 18 b 3 c − 80 a b c 2 ) d + 16 a c 4 − 4 b 2 c 3 ) e + 27 a 2 d 4 − ( 18 a b c − 4 b 3 ) d 3 − ( b 2 c 2 − 4 a c 3 ) d 2 6 3 a 3 − a ( 72 c e − 27 d 2 ) − 27 b 2 e + 9 b c d − 2 c 3 54 a 3 ) 1 3 + 24 a e − 6 b d + 2 c 2 ) 36 a 2 ( − 256 a 3 e 3 − ( − 192 a 2 b d − 128 a 2 c 2 + 144 a b 2 c − 27 b 4 ) e 2 − ( ( 144 a 2 c − 6 a b 2 ) d 2 + ( 18 b 3 c − 80 a b c 2 ) d + 16 a c 4 − 4 b 2 c 3 ) e + 27 a 2 d 4 − ( 18 a b c − 4 b 3 ) d 3 − ( b 2 c 2 − 4 a c 3 ) d 2 6 3 a 3 − a ( 72 c e − 27 d 2 ) − 27 b 2 e + 9 b c d − 2 c 3 54 a 3 ) 2 3 + ( 9 b 2 − 24 a c ) ( − 256 a 3 e 3 − ( − 192 a 2 b d − 128 a 2 c 2 + 144 a b 2 c − 27 b 4 ) e 2 − ( ( 144 a 2 c − 6 a b 2 ) d 2 + ( 18 b 3 c − 80 a b c 2 ) d + 16 a c 4 − 4 b 2 c 3 ) e + 27 a 2 d 4 − ( 18 a b c − 4 b 3 ) d 3 − ( b 2 c 2 − 4 a c 3 ) d 2 6 3 a 3 − a ( 72 c e − 27 d 2 ) − 27 b 2 e + 9 b c d − 2 c 3 54 a 3 ) 1 3 + 48 a e − 12 b d + 4 c 2 ( − 256 a 3 e 3 − ( − 192 a 2 b d − 128 a 2 c 2 + 144 a b 2 c − 27 b 4 ) e 2 − ( ( 144 a 2 c − 6 a b 2 ) d 2 + ( 18 b 3 c − 80 a b c 2 ) d + 16 a c 4 − 4 b 2 c 3 ) e + 27 a 2 d 4 − ( 18 a b c − 4 b 3 ) d 3 − ( b 2 c 2 − 4 a c 3 ) d 2 6 3 a 3 − a ( 72 c e − 27 d 2 ) − 27 b 2 e + 9 b c d − 2 c 3 54 a 3 ) 1 3 + ( − 216 a 2 d + 108 a b c − 27 b 3 ) ( − 256 a 3 e 3 − ( − 192 a 2 b d − 128 a 2 c 2 + 144 a b 2 c − 27 b 4 ) e 2 − ( ( 144 a 2 c − 6 a b 2 ) d 2 + ( 18 b 3 c − 80 a b c 2 ) d + 16 a c 4 − 4 b 2 c 3 ) e + 27 a 2 d 4 − ( 18 a b c − 4 b 3 ) d 3 − ( b 2 c 2 − 4 a c 3 ) d 2 6 3 a 3 − a ( 72 c e − 27 d 2 ) − 27 b 2 e + 9 b c d − 2 c 3 54 a 3 ) 1 3 ( − 256 a 3 e 3 − ( − 192 a 2 b d − 128 a 2 c 2 + 144 a b 2 c − 27 b 4 ) e 2 − ( ( 144 a 2 c − 6 a b 2 ) d 2 + ( 18 b 3 c − 80 a b c 2 ) d + 16 a c 4 − 4 b 2 c 3 ) e + 27 a 2 d 4 − ( 18 a b c − 4 b 3 ) d 3 − ( b 2 c 2 − 4 a c 3 ) d 2 6 3 a 3 − a ( 72 c e − 27 d 2 ) − 27 b 2 e + 9 b c d − 2 c 3 54 a 3 ) 1 3 3 a ( 36 a 2 ( − 256 a 3 e 3 − ( − 192 a 2 b d − 128 a 2 c 2 + 144 a b 2 c − 27 b 4 ) e 2 − ( ( 144 a 2 c − 6 a b 2 ) d 2 + ( 18 b 3 c − 80 a b c 2 ) d + 16 a c 4 − 4 b 2 c 3 ) e + 27 a 2 d 4 − ( 18 a b c − 4 b 3 ) d 3 − ( b 2 c 2 − 4 a c 3 ) d 2 6 3 a 3 − a ( 72 c e − 27 d 2 ) − 27 b 2 e + 9 b c d − 2 c 3 54 a 3 ) 2 3 + ( 9 b 2 − 24 a c ) ( − 256 a 3 e 3 − ( − 192 a 2 b d − 128 a 2 c 2 + 144 a b 2 c − 27 b 4 ) e 2 − ( ( 144 a 2 c − 6 a b 2 ) d 2 + ( 18 b 3 c − 80 a b c 2 ) d + 16 a c 4 − 4 b 2 c 3 ) e + 27 a 2 d 4 − ( 18 a b c − 4 b 3 ) d 3 − ( b 2 c 2 − 4 a c 3 ) d 2 6 3 a 3 − a ( 72 c e − 27 d 2 ) − 27 b 2 e + 9 b c d − 2 c 3 54 a 3 ) 1 3 + 48 a e − 12 b d + 4 c 2 ( − 256 a 3 e 3 − ( − 192 a 2 b d − 128 a 2 c 2 + 144 a b 2 c − 27 b 4 ) e 2 − ( ( 144 a 2 c − 6 a b 2 ) d 2 + ( 18 b 3 c − 80 a b c 2 ) d + 16 a c 4 − 4 b 2 c 3 ) e + 27 a 2 d 4 − ( 18 a b c − 4 b 3 ) d 3 − ( b 2 c 2 − 4 a c 3 ) d 2 6 3 a 3 − a ( 72 c e − 27 d 2 ) − 27 b 2 e + 9 b c d − 2 c 3 54 a 3 ) 1 3 ) 1 4 − 36 a 2 ( − 256 a 3 e 3 − ( − 192 a 2 b d − 128 a 2 c 2 + 144 a b 2 c − 27 b 4 ) e 2 − ( ( 144 a 2 c − 6 a b 2 ) d 2 + ( 18 b 3 c − 80 a b c 2 ) d + 16 a c 4 − 4 b 2 c 3 ) e + 27 a 2 d 4 − ( 18 a b c − 4 b 3 ) d 3 − ( b 2 c 2 − 4 a c 3 ) d 2 6 3 a 3 − a ( 72 c e − 27 d 2 ) − 27 b 2 e + 9 b c d − 2 c 3 54 a 3 ) 2 3 + ( 9 b 2 − 24 a c ) ( − 256 a 3 e 3 − ( − 192 a 2 b d − 128 a 2 c 2 + 144 a b 2 c − 27 b 4 ) e 2 − ( ( 144 a 2 c − 6 a b 2 ) d 2 + ( 18 b 3 c − 80 a b c 2 ) d + 16 a c 4 − 4 b 2 c 3 ) e + 27 a 2 d 4 − ( 18 a b c − 4 b 3 ) d 3 − ( b 2 c 2 − 4 a c 3 ) d 2 6 3 a 3 − a ( 72 c e − 27 d 2 ) − 27 b 2 e + 9 b c d − 2 c 3 54 a 3 ) 1 3 + 48 a e − 12 b d + 4 c 2 ( − 256 a 3 e 3 − ( − 192 a 2 b d − 128 a 2 c 2 + 144 a b 2 c − 27 b 4 ) e 2 − ( ( 144 a 2 c − 6 a b 2 ) d 2 + ( 18 b 3 c − 80 a b c 2 ) d + 16 a c 4 − 4 b 2 c 3 ) e + 27 a 2 d 4 − ( 18 a b c − 4 b 3 ) d 3 − ( b 2 c 2 − 4 a c 3 ) d 2 6 3 a 3 − a ( 72 c e − 27 d 2 ) − 27 b 2 e + 9 b c d − 2 c 3 54 a 3 ) 1 3 12 a − b 4 a {\displaystyle x=-{{2^{-{{3} \over {2}}}\,{\sqrt {-{{\left(18\,a^{2}\,\left({{\sqrt {-256\,a^{3}\,e^{3}-\left(-192\,a^{2}\,b\,d-128\,a^{2}\,c^{2}+144\,a\,b^{2}\,c-27\,b^{4}\right)\,e^{2}-\left(\left(144\,a^{2}\,c-6\,a\,b^{2}\right)\,d^{2}+\left(18\,b^{3}\,c-80\,a\,b\,c^{2}\right)\,d+16\,a\,c^{4}-4\,b^{2}\,c^{3}\right)\,e+27\,a^{2}\,d^{4}-\left(18\,a\,b\,c-4\,b^{3}\right)\,d^{3}-\left(b^{2}\,c^{2}-4\,a\,c^{3}\right)\,d^{2}}} \over {6\,{\sqrt {3}}\,a^{3}}}-{{a\,\left(72\,c\,e-27\,d^{2}\right)-27\,b^{2}\,e+9\,b\,c\,d-2\,c^{3}} \over {54\,a^{3}}}\right)^{{2} \over {3}}+\left(24\,a\,c-9\,b^{2}\right)\,\left({{\sqrt {-256\,a^{3}\,e^{3}-\left(-192\,a^{2}\,b\,d-128\,a^{2}\,c^{2}+144\,a\,b^{2}\,c-27\,b^{4}\right)\,e^{2}-\left(\left(144\,a^{2}\,c-6\,a\,b^{2}\right)\,d^{2}+\left(18\,b^{3}\,c-80\,a\,b\,c^{2}\right)\,d+16\,a\,c^{4}-4\,b^{2}\,c^{3}\right)\,e+27\,a^{2}\,d^{4}-\left(18\,a\,b\,c-4\,b^{3}\right)\,d^{3}-\left(b^{2}\,c^{2}-4\,a\,c^{3}\right)\,d^{2}}} \over {6\,{\sqrt {3}}\,a^{3}}}-{{a\,\left(72\,c\,e-27\,d^{2}\right)-27\,b^{2}\,e+9\,b\,c\,d-2\,c^{3}} \over {54\,a^{3}}}\right)^{{1} \over {3}}+24\,a\,e-6\,b\,d+2\,c^{2}\right)\,{\sqrt {{36\,a^{2}\,\left({{\sqrt {-256\,a^{3}\,e^{3}-\left(-192\,a^{2}\,b\,d-128\,a^{2}\,c^{2}+144\,a\,b^{2}\,c-27\,b^{4}\right)\,e^{2}-\left(\left(144\,a^{2}\,c-6\,a\,b^{2}\right)\,d^{2}+\left(18\,b^{3}\,c-80\,a\,b\,c^{2}\right)\,d+16\,a\,c^{4}-4\,b^{2}\,c^{3}\right)\,e+27\,a^{2}\,d^{4}-\left(18\,a\,b\,c-4\,b^{3}\right)\,d^{3}-\left(b^{2}\,c^{2}-4\,a\,c^{3}\right)\,d^{2}}} \over {6\,{\sqrt {3}}\,a^{3}}}-{{a\,\left(72\,c\,e-27\,d^{2}\right)-27\,b^{2}\,e+9\,b\,c\,d-2\,c^{3}} \over {54\,a^{3}}}\right)^{{2} \over {3}}+\left(9\,b^{2}-24\,a\,c\right)\,\left({{\sqrt {-256\,a^{3}\,e^{3}-\left(-192\,a^{2}\,b\,d-128\,a^{2}\,c^{2}+144\,a\,b^{2}\,c-27\,b^{4}\right)\,e^{2}-\left(\left(144\,a^{2}\,c-6\,a\,b^{2}\right)\,d^{2}+\left(18\,b^{3}\,c-80\,a\,b\,c^{2}\right)\,d+16\,a\,c^{4}-4\,b^{2}\,c^{3}\right)\,e+27\,a^{2}\,d^{4}-\left(18\,a\,b\,c-4\,b^{3}\right)\,d^{3}-\left(b^{2}\,c^{2}-4\,a\,c^{3}\right)\,d^{2}}} \over {6\,{\sqrt {3}}\,a^{3}}}-{{a\,\left(72\,c\,e-27\,d^{2}\right)-27\,b^{2}\,e+9\,b\,c\,d-2\,c^{3}} \over {54\,a^{3}}}\right)^{{1} \over {3}}+48\,a\,e-12\,b\,d+4\,c^{2}} \over {\left({{\sqrt {-256\,a^{3}\,e^{3}-\left(-192\,a^{2}\,b\,d-128\,a^{2}\,c^{2}+144\,a\,b^{2}\,c-27\,b^{4}\right)\,e^{2}-\left(\left(144\,a^{2}\,c-6\,a\,b^{2}\right)\,d^{2}+\left(18\,b^{3}\,c-80\,a\,b\,c^{2}\right)\,d+16\,a\,c^{4}-4\,b^{2}\,c^{3}\right)\,e+27\,a^{2}\,d^{4}-\left(18\,a\,b\,c-4\,b^{3}\right)\,d^{3}-\left(b^{2}\,c^{2}-4\,a\,c^{3}\right)\,d^{2}}} \over {6\,{\sqrt {3}}\,a^{3}}}-{{a\,\left(72\,c\,e-27\,d^{2}\right)-27\,b^{2}\,e+9\,b\,c\,d-2\,c^{3}} \over {54\,a^{3}}}\right)^{{1} \over {3}}}}}+\left(-216\,a^{2}\,d+108\,a\,b\,c-27\,b^{3}\right)\,\left({{\sqrt {-256\,a^{3}\,e^{3}-\left(-192\,a^{2}\,b\,d-128\,a^{2}\,c^{2}+144\,a\,b^{2}\,c-27\,b^{4}\right)\,e^{2}-\left(\left(144\,a^{2}\,c-6\,a\,b^{2}\right)\,d^{2}+\left(18\,b^{3}\,c-80\,a\,b\,c^{2}\right)\,d+16\,a\,c^{4}-4\,b^{2}\,c^{3}\right)\,e+27\,a^{2}\,d^{4}-\left(18\,a\,b\,c-4\,b^{3}\right)\,d^{3}-\left(b^{2}\,c^{2}-4\,a\,c^{3}\right)\,d^{2}}} \over {6\,{\sqrt {3}}\,a^{3}}}-{{a\,\left(72\,c\,e-27\,d^{2}\right)-27\,b^{2}\,e+9\,b\,c\,d-2\,c^{3}} \over {54\,a^{3}}}\right)^{{1} \over {3}}} \over {\left({{\sqrt {-256\,a^{3}\,e^{3}-\left(-192\,a^{2}\,b\,d-128\,a^{2}\,c^{2}+144\,a\,b^{2}\,c-27\,b^{4}\right)\,e^{2}-\left(\left(144\,a^{2}\,c-6\,a\,b^{2}\right)\,d^{2}+\left(18\,b^{3}\,c-80\,a\,b\,c^{2}\right)\,d+16\,a\,c^{4}-4\,b^{2}\,c^{3}\right)\,e+27\,a^{2}\,d^{4}-\left(18\,a\,b\,c-4\,b^{3}\right)\,d^{3}-\left(b^{2}\,c^{2}-4\,a\,c^{3}\right)\,d^{2}}} \over {6\,{\sqrt {3}}\,a^{3}}}-{{a\,\left(72\,c\,e-27\,d^{2}\right)-27\,b^{2}\,e+9\,b\,c\,d-2\,c^{3}} \over {54\,a^{3}}}\right)^{{1} \over {3}}}}}}} \over {3\,a\,\left({{36\,a^{2}\,\left({{\sqrt {-256\,a^{3}\,e^{3}-\left(-192\,a^{2}\,b\,d-128\,a^{2}\,c^{2}+144\,a\,b^{2}\,c-27\,b^{4}\right)\,e^{2}-\left(\left(144\,a^{2}\,c-6\,a\,b^{2}\right)\,d^{2}+\left(18\,b^{3}\,c-80\,a\,b\,c^{2}\right)\,d+16\,a\,c^{4}-4\,b^{2}\,c^{3}\right)\,e+27\,a^{2}\,d^{4}-\left(18\,a\,b\,c-4\,b^{3}\right)\,d^{3}-\left(b^{2}\,c^{2}-4\,a\,c^{3}\right)\,d^{2}}} \over {6\,{\sqrt {3}}\,a^{3}}}-{{a\,\left(72\,c\,e-27\,d^{2}\right)-27\,b^{2}\,e+9\,b\,c\,d-2\,c^{3}} \over {54\,a^{3}}}\right)^{{2} \over {3}}+\left(9\,b^{2}-24\,a\,c\right)\,\left({{\sqrt {-256\,a^{3}\,e^{3}-\left(-192\,a^{2}\,b\,d-128\,a^{2}\,c^{2}+144\,a\,b^{2}\,c-27\,b^{4}\right)\,e^{2}-\left(\left(144\,a^{2}\,c-6\,a\,b^{2}\right)\,d^{2}+\left(18\,b^{3}\,c-80\,a\,b\,c^{2}\right)\,d+16\,a\,c^{4}-4\,b^{2}\,c^{3}\right)\,e+27\,a^{2}\,d^{4}-\left(18\,a\,b\,c-4\,b^{3}\right)\,d^{3}-\left(b^{2}\,c^{2}-4\,a\,c^{3}\right)\,d^{2}}} \over {6\,{\sqrt {3}}\,a^{3}}}-{{a\,\left(72\,c\,e-27\,d^{2}\right)-27\,b^{2}\,e+9\,b\,c\,d-2\,c^{3}} \over {54\,a^{3}}}\right)^{{1} \over {3}}+48\,a\,e-12\,b\,d+4\,c^{2}} \over {\left({{\sqrt {-256\,a^{3}\,e^{3}-\left(-192\,a^{2}\,b\,d-128\,a^{2}\,c^{2}+144\,a\,b^{2}\,c-27\,b^{4}\right)\,e^{2}-\left(\left(144\,a^{2}\,c-6\,a\,b^{2}\right)\,d^{2}+\left(18\,b^{3}\,c-80\,a\,b\,c^{2}\right)\,d+16\,a\,c^{4}-4\,b^{2}\,c^{3}\right)\,e+27\,a^{2}\,d^{4}-\left(18\,a\,b\,c-4\,b^{3}\right)\,d^{3}-\left(b^{2}\,c^{2}-4\,a\,c^{3}\right)\,d^{2}}} \over {6\,{\sqrt {3}}\,a^{3}}}-{{a\,\left(72\,c\,e-27\,d^{2}\right)-27\,b^{2}\,e+9\,b\,c\,d-2\,c^{3}} \over {54\,a^{3}}}\right)^{{1} \over {3}}}}\right)^{{1} \over {4}}}}-{{\sqrt {{36\,a^{2}\,\left({{\sqrt {-256\,a^{3}\,e^{3}-\left(-192\,a^{2}\,b\,d-128\,a^{2}\,c^{2}+144\,a\,b^{2}\,c-27\,b^{4}\right)\,e^{2}-\left(\left(144\,a^{2}\,c-6\,a\,b^{2}\right)\,d^{2}+\left(18\,b^{3}\,c-80\,a\,b\,c^{2}\right)\,d+16\,a\,c^{4}-4\,b^{2}\,c^{3}\right)\,e+27\,a^{2}\,d^{4}-\left(18\,a\,b\,c-4\,b^{3}\right)\,d^{3}-\left(b^{2}\,c^{2}-4\,a\,c^{3}\right)\,d^{2}}} \over {6\,{\sqrt {3}}\,a^{3}}}-{{a\,\left(72\,c\,e-27\,d^{2}\right)-27\,b^{2}\,e+9\,b\,c\,d-2\,c^{3}} \over {54\,a^{3}}}\right)^{{2} \over {3}}+\left(9\,b^{2}-24\,a\,c\right)\,\left({{\sqrt {-256\,a^{3}\,e^{3}-\left(-192\,a^{2}\,b\,d-128\,a^{2}\,c^{2}+144\,a\,b^{2}\,c-27\,b^{4}\right)\,e^{2}-\left(\left(144\,a^{2}\,c-6\,a\,b^{2}\right)\,d^{2}+\left(18\,b^{3}\,c-80\,a\,b\,c^{2}\right)\,d+16\,a\,c^{4}-4\,b^{2}\,c^{3}\right)\,e+27\,a^{2}\,d^{4}-\left(18\,a\,b\,c-4\,b^{3}\right)\,d^{3}-\left(b^{2}\,c^{2}-4\,a\,c^{3}\right)\,d^{2}}} \over {6\,{\sqrt {3}}\,a^{3}}}-{{a\,\left(72\,c\,e-27\,d^{2}\right)-27\,b^{2}\,e+9\,b\,c\,d-2\,c^{3}} \over {54\,a^{3}}}\right)^{{1} \over {3}}+48\,a\,e-12\,b\,d+4\,c^{2}} \over {\left({{\sqrt {-256\,a^{3}\,e^{3}-\left(-192\,a^{2}\,b\,d-128\,a^{2}\,c^{2}+144\,a\,b^{2}\,c-27\,b^{4}\right)\,e^{2}-\left(\left(144\,a^{2}\,c-6\,a\,b^{2}\right)\,d^{2}+\left(18\,b^{3}\,c-80\,a\,b\,c^{2}\right)\,d+16\,a\,c^{4}-4\,b^{2}\,c^{3}\right)\,e+27\,a^{2}\,d^{4}-\left(18\,a\,b\,c-4\,b^{3}\right)\,d^{3}-\left(b^{2}\,c^{2}-4\,a\,c^{3}\right)\,d^{2}}} \over {6\,{\sqrt {3}}\,a^{3}}}-{{a\,\left(72\,c\,e-27\,d^{2}\right)-27\,b^{2}\,e+9\,b\,c\,d-2\,c^{3}} \over {54\,a^{3}}}\right)^{{1} \over {3}}}}} \over {12\,a}}-{{b} \over {4\,a}}}
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