Question

Resolva as equações (matriz)
| x 1 -1 |
| 1 -2 x| = -20
| 1 3 1 |

Answer 1

Resposta:

x    1    -1    x      1

1   -2    x    1     -2

1    3    1     1      3

det=-2x+x-3 -1-3x²-2=-20

-3x²-x-6=-20

-3x²-x+14=0

3x²+x-14=0

x'=[-1+√(1+168)]/6 =(-1+13)/2=6

x''=[-1-√(1+168)]/6 =(-1-13)/2=-7