Chị làm đỡ em được không

Đáp án:

Giải thích các bước giải:

$A=17+19+21+…+2021$

$=\dfrac{(2021+17)×[(2021-17):2+1]}{2}$

$=\dfrac{2038×[2004:2+1]}{2}$

$=\dfrac{2038×1003}{2}$

$=1022057$

$B=5+8+11+…+2021$

$=\dfrac{(2021+5)×[(2021-5):3+1]}{2}$

$=\dfrac{2026×[2016:3+1]}{2}$

$=\dfrac{2026×673}{2}$

$=681749$

$C=3+7+11+…+2023$

$=\dfrac{(2023+3)×[(2023-3):4+1]}{2}$

$=\dfrac{2026×[2020:4+1]}{2}$

$=\dfrac{2026×506}{2}$

$=513578$

$d,2.31.18+9.42.4+27.3.12$

$=36.31+36.42+36.27$

$=36.(31+42+27)$

$=36.100$

$=3600$

$e,36.28+36.82+64.69+64.41$

$=36.(28+82)+64.(69+41)$

$=36.110+64.110$

$=110.(36+64)$

$=110.100$

$=11000$