19° - Matemática

19/05/14

Exercícios

1)a) Determine o elemento b₂₃ da b=(bij)₃₃ com bij=i²-2j.

                bij=i²-2j

                b₂₃=2²-2.3

                b₂₃=4-6

                b₂₃=-2

    b) Sendo A=(aij)₂₃, determine a₂₁ sabendo que aij=i-j²

                aij=i-j²                                                                  2 3

                      2 3

                a₂₁=2-1²

                       2 3

                a₂₁=1-1

                           3

                a₂₁=2

                       3

 2)|  2   4   5|=| 2   4   y| x=10

     |-1   x   0|  |-1  10  0| y=5

     | 2  -1   3|  |z   -1   3| z=2

Multiplicação de Matrizes

                Existe produto A.B somente quando o número de colunas de A é igual ao número de linhas de B.

3)|2  -1   0|.| 4   5|=| 9   10|

    |4   5   x| |-1   0|  |20  56|

                     | ½   2|

1ªL 2 -1 0             1ªL 2 -1 0             2ªL 4   5 X

1ªC 4 -1 ½            2ªC 5 0 2              1ªC 4 -1 ½

       8 +1 0                 10 0 0                     16 -5 X

                                                                             2

                                                                  11+x=20
                                                                        2
                                                                  X=20-11
                                                                  2
                                                                  X=9

                                                                  2

                                                                 X=9x2
                                                                 X=18