[tex]\sqrt{25}- 2\cdot(\sqrt{49}- \sqrt{64}) - \dfrac{\sqrt1}{\sqrt{36}}=\\\\=5-2\cdot(7-8)-\dfrac16=\\\\=5-2\cdot(-1)-\dfrac16=\\\\=5+2-\dfrac16=\\\\=7-\dfrac16=\\\\=6\dfrac56[/tex]
[tex]2x+y-K=-x-2y\qquad/-2x-y\\\\-K=-3x-3y\qquad/:(-1)\\\\\underline{K=3x+3y}[/tex]
[tex]4x=-4-2x\qquad/+2x\\\\6x=-4\qquad/:6\\\\\bold{x=-\dfrac23}\\\\\\3x=5(x-1)\\\\3x=5x-5\qquad/-5x\\\\-2x=-5\qquad/:(-2)\\\\\bold{x=\dfrac52}\\\\\\-\dfrac23\cdot\dfrac52=-\dfrac53=\underline{\,-1\dfrac23\ }[/tex]
[tex]A. \\{}\quad\dfrac25:(-5)=\dfrac25\cdot\left(-\dfrac1{5}\right)=-\dfrac2{25}\\\\B.\\{}\quad \dfrac25\cdot(-5)=\dfrac25\cdot\left(-\dfrac{5}1\right)=-\dfrac{10}{5}=-\dfrac{50}{25}\\\\C.\\{}\quad\dfrac25+(-2)=\dfrac25+\left(-\dfrac{10}5\right)=-\dfrac{8}5=-\dfrac{40}{25}\\\\D.\\{}\quad-\dfrac25-2=-2\dfrac25=-\dfrac{12}5=-\dfrac{60}{25}\\\\\\-\dfrac{60}{25}\ < \, -\dfrac{50}{25}\ < \,-\dfrac{40}{25}\ < \,-\dfrac2{25}\\\\\\\large\boxed{\bold{Odp.:\ A.\ \ \frac25:(-5)}}[/tex]
