13
$\begingroup$

Could someone please explain how to solve this : $x^4 - 10x^3 + 21x^2 + 40x - 100 = 0$ - not the answer only, but a step-by-step solution. I tried to solve it, with the help of khanacademy, but still I have no idea how to correctly solve it.

Thank you so much in advance!

  • 19
    How to solve a quartic equation? Three ways: (i) Numerically; or (ii) Use the Ferrari-Cardano procedure, or one of its kin; or (iii) Pray that by design it is one of the relatively few such equations that collapse, because there are some very simple roots. Prayer works for quartics in homework exercises.2012-01-30
  • 2
    Actually, 4 ways: (iv) Use a computer. *Mathematica* solves this equation in 0.001764 seconds: `{{x -> -2}, {x -> 2}, {x -> 5}, {x -> 5}}`.2015-09-04

4 Answers 4