\(A=3.\left(\dfrac{3}{1.4}+\dfrac{3}{4.7}+..+\dfrac{3}{97.100}\right)\)
\(A=3.\left(1-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+...+\dfrac{1}{97}-\dfrac{1}{100}\right)\)
\(A=3.\left(1-\dfrac{1}{100}\right)=3.\dfrac{99}{100}=\dfrac{297}{100}\)
BT2: Tính nhanh
7)\(\dfrac{-19}{34}\left(\dfrac{17}{19}+\dfrac{49}{18}\right)+\dfrac{49}{18}\left(\dfrac{19}{34}-\dfrac{18}{7}\right)\)
8)\(\dfrac{29}{32}\left(\dfrac{41}{36}-\dfrac{32}{58}\right)-\dfrac{41}{36}\left(\dfrac{29}{32}+\dfrac{18}{41}\right)\)
Tính: -48.68+32.(-48)
1) Tìm x, biết:
a) 43+(9-21)= 317-(x+317)
b) (15-x)+(x-12)=7-(-5+x)
c) x-(5+ -(42+(-23-x)))= 13-(47+25-(32-x)))
2) Chứng tỏ rằng:
a) (a-b)-(b+c)+(c-a)-(a-b-c)= -(a+b-c)
b) (a+b-c)+(a+b)-(a-b-c)= a+b
c) -(a-b-c)+(-a+b-c)-(-a+b+c)= -(a-b+c)
Các bạn giúp mình với nhé!!! Đang gấp lắm^^
CMR :
\(A=\dfrac{1}{3}+\dfrac{1}{4}+....+\dfrac{1}{32}>2\)
E đg cần gấp lắm ạ; Mong mấy ah cj ; giải dùm ạ !!!!!!!!!!
Mơn
Bài 2 Cho M=1/31+1/32+...+1/89+1/90.So sanh M với 5/6
Giup vs mk cần gấp mk like cho
Tính nhanh:
A=18/26 + (-5)/27 + (-22)/86 + 12/39 + (-32)/43
B=(-10)/12 + 8/15 + (-19)/56 + 3/-18 + 28/60
BT2: Tính nhanh:
3) \(\dfrac{-41}{32}\left(\dfrac{15}{8}-\dfrac{16}{41}\right)+\dfrac{15}{8}\left(\dfrac{41}{32}-\dfrac{8}{3}\right)\)
4) \(\dfrac{13}{29}\left(\dfrac{29}{5}-\dfrac{45}{8}\right)-\dfrac{45}{8}\left(\dfrac{9}{8}-\dfrac{13}{29}\right)\)
32.(-39)+16.(-22)
thực hiện phép tính
a) \(\dfrac{9}{18}-\dfrac{-7}{12}+\dfrac{13}{32}\) b) \(\dfrac{5}{-8}+\dfrac{14}{39}-\dfrac{6}{10}\) c) \(\dfrac{11}{26}+\dfrac{32}{39}-\dfrac{-14}{52}\)
help me!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
