56-56=
45+10=
ai nhanh nhất tk cho
<anh hi ha nhớ trả lời nha>
10/56 + 10/140 + 10/260 + ...........+ 10/1400
Ai nhanh nhất và đúng nhất cho 10 tk
Ko thik thì cho 5 tk cũng được :)
Ai sắp thi rồi ko ?
Tôi thi còn mỗi môn toán ngày mai nên tôi vào đây luyện tập giải toán
# USAS - 12 #
\(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
đặt:\(S=\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
\(S=\frac{5}{28}+\frac{5}{70}+\frac{5}{130}+...+\frac{5}{700}\)
\(3S=\frac{3}{4.7}+\frac{3}{7.10}+\frac{3}{10.13}+...+\frac{3}{25.28}\)
\(\frac{3S}{5}=\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-...+\frac{1}{25}-\frac{1}{28}\)
\(\frac{3S}{5}=\frac{1}{4}-\frac{1}{28}\)
\(\frac{3S}{5}=\frac{3}{14}\)
\(S=\frac{3}{14}\times\frac{5}{3}\)
\(S=\frac{5}{14}\)
tính nhanh:
a, 56 x 44 + 56 x 11 + 56 x 45
b, 8 x 3 + 8 x 6 + 8
có ai đổi tk vs mk ko? ai tk mk mk tk lại
sakura
Tính nhanh:
a) 56 x 44 + 56 x 11 + 56 x 45
= 56 x ( 44 + 11 + 45 )
= 56 x 100
= 5600
b) 8 x 3 + 8 x 6 + 8
= 8 x ( 3 + 6 + 1 )
= 8 x 10
= 80
^^ Học tốt!!!
a, 56 x 44 + 56 x 11 + 56 x 45
= 56 x ( 44 + 11 + 45 )
= 56 x 100
= 5600
b, 8 x 3 + 8 x 6 + 8
= 8 x ( 3 + 6 + 1 )
= 8 x 10
= 80
tìm x biết : x+23=56
x+1223=45
ai nhanh mk tk
ai tk mk mk tk lại
* x+23=56
x =56-23
x =33
* x+1223=45
x =45-1223
x =-1178
x + 23 = 56
\(\Leftrightarrow\)x = 56 - 23 = 33
x + 1223 = 45
\(\Leftrightarrow\)x = 45 - 1223 = -1178
78 - 29 + 45 + 65 - 59 + 45 + 2 - 56 +98 - 78 + 85 - 65 + 21 + 20 - 74 = .......
Ai nhanh nhất mình cho 10 tick luôn nhé ( Chơi lớn luôn hehe )
78 - 29 + 45 + 65 - 59 + 45 + 2 - 56 +98 - 78 + 85 - 65 + 21 + 20 - 74 =98
78 - 29 + 45 + 65 - 59 + 45 + 2 - 56 +98 - 78 + 85 - 65 + 21 + 20 - 74 =
78 - 29 + 45 + 65 - 59 + 45 + 2 - 56 +98 - 78 + 85 - 65 + 21 + 20 - 74 =
1/89*1/56=? ai nhanh mk tk cho
1/89 x 1/56 = 1/4984
tk mk nha bn
Giúp giải toán
24+56+45+102+55x34-1289
Ai nhanh nhất tick cho
24 + 56 + 45 + 102 + 55 x 34 - 1289 = 808
+89+98+56=
ai nhanh nhat minh tk cho
89 + 98 + 56 = 243
tk giúp mk nha ạ!
tìm x biết : x+56=76
ai nhanh mk tk ,ai tk mk mk tk lại
tính tổng:
a) A = 1/3 + 1/3^2 + 1/3^3 +........+ 1/3^100
b) B = 10/56 + 10/140 + 10/260 +.....+ 10/1400
mọi người giúp mk vs
ai làm đc 1 trong 2 câu nhanh nhất mk sẽ tk cho
THANKS
\(A=\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+...+\frac{1}{3^{100}}\)
\(3A=1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{99}}\)
\(3A-A=\left(1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{99}}\right)-\left(\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+...+\frac{1}{3^{100}}\right)\)
\(2A=1-\frac{1}{3^{100}}\)
\(A=\frac{1-\frac{1}{3^{100}}}{2}\)
\(B=\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
\(B=\frac{5}{28}+\frac{5}{70}+\frac{5}{130}+...+\frac{5}{700}\)
\(B=\frac{5}{4.7}+\frac{5}{7.10}+\frac{5}{10.13}+...+\frac{5}{25.28}\)
\(3B=\frac{5.3}{4.7}+\frac{5.3}{7.10}+\frac{5.3}{10.13}+...+\frac{5.3}{25.28}\)
\(3B=5\left(\frac{3}{4.7}+\frac{3}{7.10}+\frac{3}{10.13}+...+\frac{3}{25.28}\right)\)
\(3B=5\left(\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}+...+\frac{1}{25}-\frac{1}{28}\right)\)
\(3B=5\left(\frac{1}{4}-\frac{1}{28}\right)\)
\(3B=5\cdot\frac{3}{14}=\frac{15}{14}\)
\(B=\frac{15}{14}:3=\frac{5}{14}\)
a) \(A=\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+...+\frac{1}{3^{100}}\)
\(3A=1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{99}}\)
\(3A-A=\left(1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{99}}\right)-\left(\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+...+\frac{1}{3^{100}}\right)\)
\(2A=1-\frac{1}{3^{100}}\)
\(\Rightarrow A=\frac{1-\frac{1}{3^{100}}}{2}\)
b) \(B=\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
\(B=\frac{5}{28}+\frac{5}{70}+\frac{5}{130}+...+\frac{5}{700}\)
\(B=\frac{5}{4.7}+\frac{5}{7.10}+\frac{5}{10.13}+...+\frac{5}{25.28}\)
\(B=\frac{5}{3}.\left(\frac{1}{4}-\frac{1}{7}\right)+\frac{5}{3}.\left(\frac{1}{7}-\frac{1}{10}\right)+\frac{5}{3}.\left(\frac{1}{10}-\frac{1}{13}\right)+...+\frac{5}{3}.\left(\frac{1}{25}-\frac{1}{28}\right)\)
\(B=\frac{5}{3}.\left(\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}+...+\frac{1}{25}-\frac{1}{28}\right)\)
\(B=\frac{5}{3}.\left(\frac{1}{4}-\frac{1}{28}\right)\)
\(B=\frac{5}{3}.\frac{3}{14}\)
\(\Rightarrow B=\frac{5}{14}\)
\(A=\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+...+\frac{1}{3^{100}}\)
\(3A=1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{99}}\)
\(3A-A=1-\frac{1}{3^{100}}\)\(\Rightarrow2A=\left(1-\frac{1}{3^{100}}\right)\Rightarrow A=\frac{1}{2}\times\left(1-\frac{1}{3^{100}}\right)\)