0}\atop{x+5>0}}\right}}\right}\\\\\mathtt{\left\{{{x+7=10(x+5)}\atop{x>-5}}\right\left\{{{9x=-43}\atop{x>-5}}\right\left\{{{x=-\frac{43}{9}}\atop{x>-\frac{45}{9}}}\right} " alt=" \displaystyle\mathtt{\lg(x+7)-\lg(x+5)=1;~\left\{{{10^{\lg(x+7)}=10^{\lg(x+5)+1}}\atop{\left\{{{x+7>0}\atop{x+5>0}}\right}}\right}\\\\\mathtt{\left\{{{x+7=10(x+5)}\atop{x>-5}}\right\left\{{{9x=-43}\atop{x>-5}}\right\left\{{{x=-\frac{43}{9}}\atop{x>-\frac{45}{9}}}\right} " align="absmiddle" class="latex-formula">