1)-3<x
\\\\\\\\\\\\\\\\\\\\\\\\
-------------------------o-----------------------> x
-3
x∈(-3; + бесконечность)
<span>2)-2<x<u><</u>9
\\\\\\\\\\\\\\\\\\\\\
//////////////////////////
</span>--------------о-----------o-----------------------> x<span>
-2 9
х</span>∈(-2; 9]
<span>
</span><span>3)-2<x
////////////////////////
</span>-------------------------o-----------------------> x<span>
-2
x</span>∈(-2; + бесконечность)
<span>
</span><span>4)-5<x<u><</u>7
\\\\\\\\\\\\\\\\\\\\\\\\\\
////////////////////////////
</span>--------------о-----------o-----------------------> x
-5 7
х∈(-5; 7]
Для решения используется теорема косинусов.