1)$\genfrac{}{}{0ex}{}{1}{2\cdot 5}+\genfrac{}{}{0ex}{}{1}{5\cdot 8}+...+\genfrac{}{}{0ex}{}{1}{x\left(x+3\right)}=\genfrac{}{}{0ex}{}{11}{70}$

$\left(\genfrac{}{}{0ex}{}{3}{2\cdot 5}+\genfrac{}{}{0ex}{}{3}{5\cdot 8}+...+\genfrac{}{}{0ex}{}{3}{x\left(x+3\right)}\right):3=\genfrac{}{}{0ex}{}{11}{70}$

$\left(\genfrac{}{}{0ex}{}{1}{2}-\genfrac{}{}{0ex}{}{1}{5}+\genfrac{}{}{0ex}{}{1}{5}-\genfrac{}{}{0ex}{}{1}{8}+.....+\genfrac{}{}{0ex}{}{1}{x}-\genfrac{}{}{0ex}{}{1}{x+3}\right)=\genfrac{}{}{0ex}{}{11}{70}\cdot 3$

$\genfrac{}{}{0ex}{}{1}{2}-\genfrac{}{}{0ex}{}{1}{x+3}=\genfrac{}{}{0ex}{}{33}{70}$

$\genfrac{}{}{0ex}{}{1}{x+3}=\genfrac{}{}{0ex}{}{1}{2}-\genfrac{}{}{0ex}{}{33}{70}$

$\genfrac{}{}{0ex}{}{1}{x+3}=\genfrac{}{}{0ex}{}{2}{70}$

$\genfrac{}{}{0ex}{}{1}{x+3}=\genfrac{}{}{0ex}{}{1}{35}$

$x+3=35x=35-3x=32$

2) Số góc đc tạo thành từ 2023 tia chung gốc là:$\genfrac{}{}{0ex}{}{2023\cdot 2022}{2}=2045253$ (góc)

hỗn số : $3\genfrac{}{}{0ex}{}{1}{2}$

27

70

76-32=44

10+23=33

1-1=0

Fujiko Fujio

128+452+872

=(128+872)+452

=1000+452

=1452