Question

am nevoie urgent de ajutor va rog frumos dau coroana​

Answer 1

 

$\displaystyle\bf\\^\star7)\\\\\Big[\underbrace{1-2+3-4+...+99-100}_{100~de~termeni}\Big]\cdot\frac{3}{25}+\Big(-6\Big)^2=\\\\=\Big[\underbrace{(1-2)+(3-4)+...+(99-100)}_{100~:~2~=~50~de~paranteze}\Big]\cdot\frac{3}{25}+\Big(-6\Big)^2=\\\\=\Big[\underbrace{(-1)+(-1)+...+(-1)}_{50~de~"(-1)"}\Big] \cdot\frac{3}{25}+\Big(-6\Big)^2=\\\\=\Big[50\times(-1)\Big] \cdot\frac{3}{25}+36=\\\\=-50 \cdot\frac{3}{25}+36=\\\\=-2 \cdot3+36=\\\\=-6+36=\boxed{\bf30}$