Bantu dong please :( nomor 3 4 dan 5 tolong yah :(

Bantu dong please 🙁 nomor 3 4 dan 5 tolong yah 🙁

No 3.
$left[begin{array}{ccc}5&a&3\b&2&cend{array}right] = left[begin{array}{ccc}5&2&3\2a&2&abend{array}right]$
cari yg seletak, maka:
*a = 2
*b=2a
b=2×2=4
*c=a.b
c=2×4=8
jadi a+b+c=2+4+8=14

4.
$left[begin{array}{ccc}3&1\2&-2end{array}right] + left[begin{array}{ccc}2&10\-2&4end{array}right] = left[begin{array}{ccc}5&1\0&2end{array}right]$
(A+2B)⁻¹ = 5×2 – 11×0
= 10

5.
$left[begin{array}{ccc}1&2\4&3end{array}right] X left[begin{array}{ccc}3&1\-2&-3end{array}right] = left[begin{array}{ccc}-1&-5\-6&-5\end{array}right]$

koreksi lagi ya :3

yg bonus
5x+y=-5 x2 10x+2y=-10
2x+2y=14 x5 10x+10y=70
   —————— –
   -8y=-80
   y=10

subsitusikan ke salah satu nya :
5x+y=-5
5x+10=-5
5x=-5-10
5x=-15
x=-3

No.3
jawab: a = 2
b = 2a ⇔2.2 = 4
c = ab ⇔ 2.4 = 8
jadi a+b+c = 2+4+8 =14

no.4
jawab = $left[begin{array}{ccc}3&1\2&-2end{array}right] + 2 left[begin{array}{ccc}1&5\-1&2end{array}right]$
= $left[begin{array}{ccc}3&1\2&-2end{array}right] + left[begin{array}{ccc}2&10\-2&4end{array}right]$
= $left[begin{array}{ccc}6-2&30+4\4+4&20-8end{array}right]$
= $left[begin{array}{ccc}4&34\8&16end{array}right]$
det $left[begin{array}{ccc}4&34\8&16end{array}right]$ = 64-272 = -208
adjoint = $left[begin{array}{ccc}4&34\8&16end{array}right]$
= $left[begin{array}{ccc}16&-34\-8&4end{array}right]$
$(A+2B) ^{-1}$ = $left[begin{array}{ccc}-1/13&17/104\1/26&-1/52end{array}right]$

maaf kalo salah ya..