x^2+20x+100-x^2+10x-25=30x+75 " alt="(x+10)^2=(5-x)^2 => x^2+20x+100-x^2+10x-25=30x+75 " align="absmiddle" class="latex-formula">
30x=-75 =>x = \frac{-75}{30} = -\frac{5}{2} " alt="30x+75=0 => 30x=-75 =>x = \frac{-75}{30} = -\frac{5}{2} " align="absmiddle" class="latex-formula">