5x+2>0 одна четвертая x>1

3) $\left \{ {{3x-9\ \textless \ 0} \atop {5x+2\ \textgreater \ 0}} \right. \ \textless \ =\ \textgreater \ \left \{ {{3x\ \textless \ 9} \atop {5x\ \textgreater \ -2}} \right. \ \textless \ =\ \textgreater \ \left \{ {{x\ \textless \ 3} \atop {x\ \textgreater \ -0.4}} \right.$

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-----------o------------o------->x

-0.4 3

x∈(-0.4; 3)

1) 5х+2>0

5x > -2

x > -2/5

x > -0.4

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--------o------------>x

-0.4

x∈(-0.4; +∞)

2) 1/4 x >1 | * 4

x > 4

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--------o---------->x

x∈(4; +∞)