Номер 3. Запиши сразу что 
0" alt="\sqrt{x+11} >0" align="absmiddle" class="latex-formula">
x^{2}+11=x^{2}-2x+1=>x+11-x^{2} +2x-1=0=>-x^{2}+3x+10=0=>D=b^{2}-4ac=9-4*(-1)*10=49=>x1=\frac{-3+7}{-2}=-2=>x2=\frac{-3-7}{-2}=5" alt="\sqrt{x+11} = x-1=>x^{2}+11=x^{2}-2x+1=>x+11-x^{2} +2x-1=0=>-x^{2}+3x+10=0=>D=b^{2}-4ac=9-4*(-1)*10=49=>x1=\frac{-3+7}{-2}=-2=>x2=\frac{-3-7}{-2}=5" align="absmiddle" class="latex-formula">