4.
S = =
Ответ: 12,5
5.
7.
-\frac{7}{4}\\ 4x +7=7^{2} \\4x+7=49\\4x=49-7\\4x=42\\x=\frac{21}{2} = 10\frac{1}{2} = 10,5" alt="log_{7} (4x+7) = 2; x> -\frac{7}{4}\\ 4x +7=7^{2} \\4x+7=49\\4x=49-7\\4x=42\\x=\frac{21}{2} = 10\frac{1}{2} = 10,5" align="absmiddle" class="latex-formula">