<span>5х+3у=21
5х-3у=1</span>
10x=22
x=2.2
5*2.2+3y=21
3y=10
y=10/3
<u><em>Ответ: (2,2; 10/3)</em></u>
В=12
a8=a1+7d
54=a1+84
a1=-30
-30 -18 -6 6 18 30 42 54 66 78
с четвертого плюс
<span>{ 5 - 3x >= -1 { 3 - 4x >= 8 => { 3x =< 6 { 4x =< -5 => { x =< 2 { x =< -5\4 => x=< -</span><span />
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