Toán Lớp 6: B1:Tực hiện phép tính a,-1/39+-1/52 b,-6/9+-12/16 c,-2/5-3/11 d,-34/37.74/-85 e,-5/9:-7/18 f

Question

Toán Lớp 6:  B1:Tực hiện phép tính a,-1/39+-1/52         b,-6/9+-12/16        c,-2/5-3/11          d,-34/37.74/-85         e,-5/9:-7/18            f,3/7+(-5/2)+(-3/5)        g,4/5-(-2/7)-7/10 cảm ơn ạ

myngocla · Answer

#Bẻox_Rebecca     text{Giải đáp:}    a,  $ dfrac{-1}{39}$+$ dfrac{-1}{52}$     =$ dfrac{-7}{156}$      b, $ dfrac{-6}{9}$+$ dfrac{-12}{16}$       =$ dfrac{-17}{12}$      c, $ dfrac{-2}{5}$-$ dfrac{3}{11}$       =$ dfrac{-37}{55}$       d,$ dfrac{-34}{37}$.$ dfrac{74}{-85}$       =$ dfrac{4}{5}$       e, $ dfrac{-5}{9}$:$ dfrac{-7}{18}$       =$ dfrac{10}{7}$       f, $ dfrac{3}{7}$+($ dfrac{-5}{2}$)+($ dfrac{-3}{5}$)       =$ dfrac{-29}{41}$+$ dfrac{-3}{5}$       =$ dfrac{-187}{70}$       g, $ dfrac{4}{5}$-($ dfrac{-2}{7}$)-($ dfrac{7}{10}$)       =$ dfrac{38}{25}$-$ dfrac{7}{10}$       =$ dfrac{27}{70}$

quynhthanhnhu · Answer

a,-1/39+(-1/52)     =-( 1/39+1/52)       =-(52/2028+39/2028)     =-91/2028     =-7/156      b,-6/9+(-12/16)     =-(6/9+3/4)     =-(24/36+18/36)     =-42/36     =1 1/6     c,-2/5-3/11     =-2/5+(-3/11)     =-22/55+(-15/55)     =-37/55     d,-34/37 . 74/-85    =$ dfrac{(-34).74}{37.(-85)}$   =$ dfrac{(-17).2.2.37}{37.(-17).5}$   =4/5    e,-5/9:-7/18     =-5/9.-18/7     =$ dfrac{(-5).(-18)}{9.7}$     =$ dfrac{(-5).(-2)}{7}$     =10/7     f,3/7+(-5/2)+(-3/5)     =6/14+(-35/14)+(-3/5)     =$ dfrac{6+(-35)}{14}$ +(-3/5)     =$ dfrac{-9}{14}$ +(-3/5)     =$ dfrac{-45}{70}$+$ dfrac{-42}{70}$     =-87/70     g,4/5-(-2/7)-7/10     =,4/5+2/7-7/10     =4/5-7/10+2/7     =8/10-7/10+2/7     =1/10+2/7     =7/70+20/70     =27/70