1/Tìm x, biết:
(2/11.13 + 2/13.15 +...+ 2/19.21) - x + 4 + 221/231 = 7/3
Tìm x biết (2/11.13+2/13.15+...+2/19.21)-x+ 4+221/231=7/3
(2/11.13+2/13.15+...+2/19.21)-x+4+221/231=7/3
(1/11-1/13+1/13-1/15+...+1/19-1/21)-x+4+221/231=7/3
(1/11-1/21)-x+4+221/231 =7/3
(21/231-11/231)-x+4+221/231 =7/3
10/231-x+4+221/231 =7/3
(10/231+221/231)-x+4 =7/3
231/231-x+4 =7/3
1-x+4 =7/3
-x+5 =7/3
-x =7/3-5
-x =7/3-15/3
-x =-8/3
x =8/3
ĐẶt A = 2/11.13 + 2/13.15 +...+2/19.21
A = 1/11 - 1/13 +1/ 13 -1/15 +....+1/19 - 1/21
A = 1/11 - 1/21
A = 10/231
Thay vào ta có
10/231 - x + 4 + 221 /231 = 7/3
-x + 4 + 1 = 7/3 ( vì 10/231 + 221/231 = 1)
-x + 5 = 7/3
-x = 7/3 - 5
-x = -8/3
x = 8/3
( 2/11.13 + 2/13.15 + ..... + 2/19.21 ) -x + 221/231 =4/3
tìm x, biết
2/11.13 + 2/13.15 +........2/19.21 -x + 221/231 = 4/3
help mk vs, nhanh lên nha!
\(\frac{2}{11.13}+\frac{2}{13.15}+...+\frac{2}{19.21}-x+\frac{221}{231}=\frac{4}{3}\)
\(=2\left(\frac{1}{11.13}+\frac{1}{13.15}+...+\frac{1}{19.21}\right)-x+\frac{221}{231}=\frac{4}{3}\)
\(=2.\frac{1}{2}\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+...+\frac{1}{19}-\frac{1}{21}\right)-x+\frac{221}{231}=\frac{4}{3}\)
\(=\left(\frac{1}{11}-\frac{1}{21}\right)-x+\frac{221}{231}=\frac{4}{3}\)
\(=\frac{10}{231}-x+\frac{221}{231}=\frac{4}{3}\)
\(\frac{10}{231}-x=\frac{4}{3}-\frac{221}{231}\)
\(\frac{10}{231}-x=\frac{29}{77}\)
\(x=\frac{10}{231}-\frac{29}{77}\)
\(x=\frac{-1}{3}\)
có cần cầu kì vậy ko bn, còn cách nào dễ hỉu hơn ko
Tìm x:
\((\frac{2}{11.13}+\frac{2}{13.15}+...+\frac{2}{19.21})-x+\frac{221}{231}=\frac{4}{3}\)
tìm x biết:
a, (11/12+11/12.23+11/23.24+...+11/89.100)+x=2/3
b, (2/11.13+2/13.15)+...+2/19.21)-x+221/231=4/3
Giúp mk nha ai giải đc mk tick cho nhé!
1,tìm x
a, 4/7+5/7:x=1
b,(2/11. 2/13.15+...+2/19.21) - x + 221/231=4/3
a)\(\frac{5}{7}:X=1-\frac{4}{7}=\frac{3}{7}\)
\(X=\frac{5}{7}:\frac{3}{7}=\frac{5}{3}\)
b)
\(\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{14}+...+\frac{1}{19}-\frac{1}{21}\right)-X=\frac{4}{3}-\frac{221}{231}=\frac{29}{77}\)
\(\left(\frac{1}{11}-\frac{1}{21}\right)-X=\frac{29}{77}\)
\(X=\frac{10}{231}-\frac{29}{77}=-\frac{1}{3}\)
xem xong nhớ tích
tìm x, biết
a, \(\left(\frac{11}{12}+\frac{11}{12.23}+\frac{11}{23.24}+...+\frac{11}{89.100}\right)+x=\frac{5}{3}\)
b, \(\left(\frac{2}{11.13}+\frac{2}{13.15}+...+\frac{2}{19.21}\right)-x+4+\frac{221}{231}=\frac{7}{3}\)
(2/11.13)+...+(2/19.21)-x+4+221/231=7/3
. Tìm x, biết :
a) ( 11/12 + 11/12.23 + 11/23.24 + ... + 11/89.100 ) + x = 2/3
b) ( 2/11.13 + 2/13.15 + ... + 2/19.21 ) - x + 221/231 = 4/3
a.
\(\left(\frac{11}{12}+\frac{11}{12\times23}+\frac{11}{23\times34}+...+\frac{11}{89\times100}\right)+x=\frac{2}{3}\)
\(\left(\frac{11}{12}+\frac{1}{12}-\frac{1}{23}+\frac{1}{23}-\frac{1}{34}+...+\frac{1}{89}-\frac{1}{100}\right)+x=\frac{2}{3}\)
\(\left(\frac{11}{12}+\frac{1}{12}-\frac{1}{100}\right)+x=\frac{2}{3}\)
\(\left(\frac{12}{12}-\frac{1}{100}\right)+x=\frac{2}{3}\)
\(\left(1-\frac{1}{100}\right)+x=\frac{2}{3}\)
\(\left(\frac{100-1}{100}\right)+x=\frac{2}{3}\)
\(\frac{99}{100}+x=\frac{2}{3}\)
\(x=\frac{2}{3}-\frac{99}{100}\)
\(x=\frac{200-297}{300}\)
\(x=-\frac{97}{300}\)
b.
\(\left(\frac{2}{11\times13}+\frac{2}{13\times15}+...+\frac{2}{19\times21}\right)-x+\frac{221}{231}=\frac{4}{3}\)
\(\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+...+\frac{1}{19}-\frac{1}{21}\right)+\frac{221}{231}-x=\frac{4}{3}\)
\(\left(\frac{1}{11}-\frac{1}{21}\right)+\frac{221}{231}-x=\frac{4}{3}\)
\(\left(\frac{21-11}{231}\right)+\frac{221}{231}-x=\frac{4}{3}\)
\(\frac{10}{231}+\frac{221}{231}-x=\frac{4}{3}\)
\(\frac{231}{231}-x=\frac{4}{3}\)
\(1-x=\frac{4}{3}\)
\(x=1-\frac{4}{3}\)
\(x=\frac{3-4}{3}\)
\(x=-\frac{1}{3}\)
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