UNIVERSIDADE ESTADUAL DE RORAIMA
PRÓ-REITORIA DE ENSINO E GRADUAÇÃO
COORDENAÇÃO DE AGRÁRIAS
CURSO DE ENGENHARIA FLORESTAL
DISCIPLINA: Álgebra Básica
PROFº: EVERALDO BARRETO DA SILVA
ACADÊMICO: Amanda Nathália Melo de Jesus.
DATA: 06/11/2020
Atividade Proposta 03 de Multiplicação de Matrizes e Matriz Inversa
1) Resposta:
a)
A . B =
[
2−3−5
−1 4 5
1−3−4
]
×
[
−1 3 5
1−3−5
1 3 5
]
[
2×
(
−1
)
+
(
−3
)
×1+
(
−5
)
×1 2×3+
(
−3
)
×
(
−3
)
+
(
−5
)
×3 2 ×5+
(
−3
)
×
(
−5
)
+
(
−5
)
×5
−1×
(
−1
)
+4×1+5×1−1×3+4×
(
−3
)
+5×3−1×5+4×
(
−5
)
+5×5
1×
(
−1
)
+
(
−3
)
×1+
(
−4
)
×1 1 ×3+
(
−3
)
×
(
−3
)
+
(
−4
)
×3 1×5+
(
−3
)
×
(
−5
)
+
(
−4
)
×5
]
[
−2−3−5 6+9−15 10 +15−25
1+4+5−3−12+15 −5−20 +25
−1−3−4 3+9−12 5 +15−20
]
=
[
−10 0 0
10 0 0
−8 0 0
]
b)
B . A =
[
−1 3 5
1−3−5
1 3 5
]
×
[
2−3−5
−1 4 5
1−3−4
]
[
−1×2+3×
(
−1
)
+5×1−1×
(
−3
)
+3×4+5×
(
−3
)
−1×5+3×5+5×
(
−4
)
1×2+
(
−3
)
×
(
−1
)
+
(
−5
)
×1 1×
(
−3
)
+
(
−3
)
×4+
(
−5
)
×
(
−3
)
1×5+
(
−3
)
×5+
(
−5
)
×
(
−4
)
−1×2+3×
(
−1
)
+5×1−1×
(
−3
)
+3×4+5×
(
−3
)
−1×5+3×5+5×
(
−4
)
]
[
−2−3+5 3+12−15 −5+15 −20
2+3−5−3−12+15 5−15 +20
2−3+5 3+12−15 −5+15 −20
]
=
[
0 0 −10
0 0 10
0 0 −10
]
c)
A . C =
[
2−3−5
−1 4 5
1−3−4
]
×
[
2−2−4
−1 3 4
1−2−3
]
[
2×2+
(
−3
)
×
(
−1
)
+5×1 2 ×
(
−2
)
+
(
−3
)
×3+5×
(
−2
)
2×
(
−4
)
+
(
−3
)
×4+5×
(
−3
)
−1×2+4×
(
−1
)
+5×1−1×
(
−2
)
+4×3+5×
(
−2
)
−1×
(
−4
)
+4×4+5×
(
−3
)
1×2+
(
−3
)
×
(
−1
)
+
(
−4
)
×1 1 ×
(
−2
)
+
(
−3
)
×3+
(
−4
)
×
(
−2
)
1×
(
−4
)
+
(
−3
)
×4+
(
−4
)
×
(
−3
)
]
[
4+3+5−4−9−10 −8−12−15
−2−4+5 2+12−10 4 +16 −15
2+3−4−2−9+8−4−12+1 2
]
=
[
12 −23 −35
−1 4 5
1−3−4
]
d)
C . A=
[
2−2−4
−1 3 4
1−2−3
]
×
[
2−3−5
−1 4 5
1−3−4
]
