Question

X^3-9x-440=0 (not using factor theorem) and show me how to work it out

Answer 1

We use the method of briot ruffin.

Where,
The possible roots are the 440 splitters divided by the coefficient divisors a.

Divisors of 440 = 440, 220, 110, 88, 55, 44, 40 , 22 , 20 , 11, 10, 8, 5, 4, 2, 1

Testinh the values, We will see:

440 / 55 = 8

This would be one root correct

Then,

x^3 -9x -440 =0

1x^3 + 0x^2 -9x - 440 = 0

1 , 0 , -9 , -440 | 8

Downing the number 1, we stay:


1 , 0 , -9, -440 | 8

, 8 , 64 , 440

1x^2 + 8x + 55 = 0

Ussing the method of baskara

a = 1
b = 8
c = 55

Delta = b^2 - 4ac

Delta = 8^2 - 4.(1).(55)

Delta = 64 - 220

Delta = - 156

To this negative value , Not there is real root.


Then, just x = 8 It is real.

Answer :

X = 8