-1\\O.D.3.:\;7x+3>0\Rightarrow x>-\frac37\\\\7x+3<(0,3)^{-1}\\7x+3<\frac1{0,3}\\7x+3<\frac{10}3\\7x<\frac{10}3-3\\7x<\frac13\\x<\frac1{21}\\c\;O.D.3.\;x\in\left(-\frac37;\;\frac1{21}\right)" alt="\log_{0,3}(7x+3)>-1\\O.D.3.:\;7x+3>0\Rightarrow x>-\frac37\\\\7x+3<(0,3)^{-1}\\7x+3<\frac1{0,3}\\7x+3<\frac{10}3\\7x<\frac{10}3-3\\7x<\frac13\\x<\frac1{21}\\c\;O.D.3.\;x\in\left(-\frac37;\;\frac1{21}\right)" align="absmiddle" class="latex-formula">