1, tinh
a, 31×72+ (-31) ×70-31×(-1)
b,[3 ×(-2)/(-8)]×(-7)-(-2)×(-5)
c,(-3)^2+ 3^2-(-2)^3×(-3)^0
d,(-2)×(-3)÷(-1)-(-3)×(-2) ÷ (-6)+(-2)
e,[20×2^4-12×2^3+48×2^2]÷(-8)
1, tinh
a, 31×72+ (-31) ×70-31×(-1)
b,[3 ×(-2)/(-8)]×(-7)-(-2)×(-5)
c,(-3)^2+ 3^2-(-2)^3×(-3)^0
d,(-2)×(-3)÷(-1)-(-3)×(-2) ÷ (-6)+(-2)
e,[20×2^4-12×2^3+48×2^2]÷(-8)
1)\(\dfrac{1}{2}+\dfrac{13}{19}-\dfrac{4}{9}+\dfrac{6}{19}+\dfrac{5}{18}\)
2)\(\dfrac{ }{\dfrac{-20}{23}+\dfrac{2}{3}-\dfrac{3}{23}+\dfrac{2}{5}+\dfrac{7}{15}}\)
3)\(\dfrac{ }{\dfrac{4}{3}+\dfrac{-11}{31}+\dfrac{3}{10}-\dfrac{20}{31}-\dfrac{2}{5}}\)
4)\(\dfrac{ }{\dfrac{5}{7}.\dfrac{5}{11}+\dfrac{5}{7}.\dfrac{2}{11}-\dfrac{5}{7}.\dfrac{14}{11}}\)
A=3+31+2+31+2+3+.....+31+2+3+4+...+100
tính A
BT1 :thực hành phép tính
4/3+-11/31+3/10-20/31-2/5
7/12-1/-16+3/4
2/11.-5/4+-9/11.5/4+ 1 và 3/4
-9/27-25/75
BT2: tìm x, biết
5/7-3/7.x=1
x+2/3=-1/12.-4/5
x-4=-14/35:7/5
tìm x thuộc Z
a) 1/3 + (-2)/5 + 1/6 + (-1)/5 < x < ( -3)/4 + 2/7 + (-1)/4 + 3/5 + 5/7
b) 5/17 + (-4)/9 + (-20)/31 + 12/17 + (-11)/31 < x/9 < (-3)/7 + 7/15 + 4/(-7) + 8/15 +2/3
4/3 + -11/31 + 3/10 - 20/31 - 2/5
c,31 . 72 - 31 x 70 - 31 x2 - 31
d, 25 x 32 - 47 - 32 x ( 25 - 47 )
e, (- 3 ) ^2 + 3^3 - ( 3)^0
g, 125 x ( -61) x ( - 2 )^3 x ( - 1 ) ^ 2n
\(A=1+3+3^2+3^4+3^5+3^6+...+3^{31}.Chgtỏ13⋮\)
tinh: a) 5.( -3)2 -14.(-8)+(- 31)
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b) -31 –{82 – (-17)}
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