Question

calcule a soma da diagonal principal da matriz A 3,3 [aij] com Aij i+2j.

Answer 1

A - 3x3
[aij]

$\left[\begin{array}{ccc}a11&a12&a13\\a21&a22&a23\\a31&a32&a33\end{array}\right]$

aij = i+2j

a11= 1+2.1=3
a12= 1+2.2=5
a13= 1+2.3=7
a21= 2+2.1=4
a22= 2+2.2=6
a23= 2+2.3=8
a31= 3+2.1=5
a32= 3+2.2=7
a33= 3+2.3=9

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$\left[\begin{array}{ccc}3&5&7\\4&6&8\\5&7&9\end{array}\right]$


Os elementos da diagonal principal são: 3, 6 e 9

3+6+9=18