# Y^3-7y+6=? How solve this

1
by vishalac01

2015-06-07T23:08:40+05:30

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Cubic equation / cubic polynomial  :  x³ - 3 p x - 2 q = 0
Solution is given by:

Or, by:

Given  y³ - 7 y + 6 = 0
So substituting      p = 7/3    and    q = -3  we get :

We can try to find the solutions of  the polynomial equation: y³ - 7 y + 6 = 0  by
constant term / coefficient of y³:    +or -  6 /1  or its factors :  + or - of 6, 3, 2, 1
So we can try these 8 possibilities.  It so happens that 1, 2, -3 are the roots.

By using the other formula :

This solution gives complex numbers.  So it requires to convert them in the polar coordinate form    and then take cube root and then add the two cube roots.
Then we get the same answers.

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