31-40= 31+ ( -40) = -( 40 - 31)= -9
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31-40= 31+ ( -40) = -( 40 - 31)= -9
30 + 31 + 31 + ... + 40 = ?
31 . 15 . 7 2 . 4 - 31 . 49 . 40
31 nhân 15 nhân 7mũ2 nhân 4 trừ 31 nhân 49 nhân 40
tính:
a) \(\dfrac{-5}{13}\)+\(\dfrac{8}{13}\) b) \(\dfrac{5}{31}\)+\(\dfrac{-22}{31}\) c) \(\dfrac{-13}{43}\)+\(\dfrac{-40}{43}\)
d) \(\dfrac{-3}{29}\)-\(\dfrac{16}{58}\) e) \(\dfrac{8}{40}\)-\(\dfrac{-36}{45}\) f) \(\dfrac{-8}{18}\)-\(\dfrac{-15}{27}\) g)(-2)+\(\dfrac{-5}{8}\)
30+31+32+...+40
30+31+32+...+40
Tính 31+32+.....+40
30 + 31 + 32 + .........+ 40 =
30 + 31 + 32 + .................. + 40 = ?