-3/7+15/26-(2/13-3/7)
tính nhanh ạ
giúp mik vs
thanks
K
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NT
0
2 tháng 5 2021
a. \(\frac{-3}{7}+\frac{15}{26}-\frac{2}{13}+\frac{3}{7}\)
\(=\left(\frac{-3}{7}+\frac{3}{7}\right)+\frac{15}{26}-\frac{2}{13}\)
\(=\frac{15}{26}-\frac{2}{13}\)
\(=\frac{15}{26}-\frac{4}{26}=\frac{11}{26}\)
b. \(\frac{3}{7}-\frac{5}{3}\div\frac{1}{9}-\frac{3}{7}\)
\(=\frac{3}{7}-\frac{5}{3}\times\frac{9}{1}-\frac{3}{7}\)
\(=\frac{3}{7}-15-\frac{3}{7}\)
\(=-15\)
2 tháng 5 2021
\(-\frac{3}{7}+\frac{15}{26}-\frac{2}{13}+\frac{3}{7}=\frac{15}{26}-\frac{2}{13}=\frac{11}{26}\)
\(\frac{2.3}{7}-\frac{5}{3}:\frac{1}{9}-\frac{3}{7}=\frac{6}{7}-15-\frac{3}{7}=\frac{3}{7}-15=-\frac{102}{7}\)
KN
0
AN
30 tháng 12 2017
c) (x + 9 - 17) - 24 = 11 - (x + 7)
(x + 8) - 24 = 11 - (x + 7)
(x + 8) - 24 = 11 - x - 7
x-8-24=11-x-7
x-8-24=4-x
x -32 = 4 -x
x + x -32 =4
x + x = 4 +32
2x=36
x=18
AN
30 tháng 12 2017
a) -5x - 25 = 3x + 23
-5x - 32 = 3x + 8
-5x - 3x - 32 = 8
-5x - 3x = 8 +32
-8x = 8+32
-8x = 40
x= -5
VT
20 tháng 8 2017
\(a,=\frac{7-1}{1.3.7}+\frac{9-3}{3.7.9}+\frac{13-7}{7.9.13}+\frac{15-9}{9.13.15}\)\(+\frac{19-13}{13.15.19}\)
\(=\frac{1}{1.3}-\frac{1}{3.7}+\frac{1}{3.7}-\frac{1}{7.9}+\frac{1}{7.9}-\frac{1}{9.13}+\frac{1}{9.13}-\frac{1}{13.15}+\frac{1}{13.15}-\frac{1}{15.19}\)
\(=\frac{1}{1.3}-\frac{1}{15.19}=\frac{95}{285}-\frac{1}{285}=\frac{94}{285}\)
\(b,=\frac{1}{6}.\left(\frac{6}{1.3.7}+\frac{6}{3.7.9}+\frac{6}{7.9.13}+\frac{6}{9.13.15}+\frac{6}{13.15.19}\right)\)
làm giống như trên
\(c,=\frac{1}{8}.\left(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+...+\frac{1}{48.49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{2}{1.2.3}+\frac{2}{2.3.4}+\frac{2}{3.4.5}+...+\frac{2}{48.49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{3-1}{1.2.3}+\frac{4-2}{2.3.4}+\frac{5-3}{3.4.5}+...+\frac{50-48}{48.49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{1}{1.2}-\frac{1}{2.3}+\frac{1}{2.3}-\frac{1}{3.4}+\frac{1}{3.4}-\frac{1}{4.5}+...+\frac{1}{48.49}-\frac{1}{49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{1}{2}-\frac{1}{2450}\right)=\frac{1}{16}.\left(\frac{1225}{2450}-\frac{1}{2450}\right)=\frac{153}{4900}\)
\(d,=\frac{5}{7}.\left(\frac{7}{1.5.8}+\frac{7}{5.8.12}+\frac{7}{8.12.15}+...+\frac{7}{33.36.40}\right)\)
\(=\frac{5}{7}.\left(\frac{8-1}{1.5.8}+\frac{12-5}{5.8.12}+\frac{15-8}{8.12.15}+...+\frac{40-33}{33.36.40}\right)\)
\(=\frac{5}{7}.\left(\frac{1}{1.5}-\frac{1}{5.8}+\frac{1}{5.8}-\frac{1}{8.12}+\frac{1}{8.12}-\frac{1}{12.15}+...+\frac{1}{33.36}-\frac{1}{36.40}\right)\)
\(=\frac{5}{7}.\left(\frac{1}{5}-\frac{1}{1440}\right)=\frac{5}{7}.\left(\frac{288}{1440}-\frac{1}{1440}\right)=\frac{41}{288}\)
P/S: . là nhân nha
NB
5
2 tháng 5 2017
\(\frac{-3}{7}+\frac{15}{26}-\left(\frac{2}{13}-\frac{3}{7}\right)=\frac{-3}{7}+\frac{15}{26}-\frac{2}{13}+\frac{3}{7}\)
\(=\left(\frac{-3}{7}+\frac{3}{7}\right)+\left(\frac{15}{26}-\frac{2}{13}\right)\)
\(=0+\left(\frac{15}{26}-\frac{4}{26}\right)\)
\(=\frac{11}{26}\)
2 tháng 5 2017
\(\frac{-3}{7}+\frac{15}{26}-\left(\frac{2}{13}-\frac{3}{7}\right)\)
=\(\frac{-3}{7}+\frac{15}{26}-\left(\frac{-2}{13}\right)+\frac{3}{7}\)
=\(\frac{-3}{7}+\frac{15}{26}+\frac{2}{13}+\frac{3}{7}\)
=\(\left(\frac{-3}{7}+\frac{3}{7}\right)+\frac{15}{26}+\frac{2}{13}\)
=\(0+\frac{19}{26}\)
=\(\frac{19}{26}\)
Nếu đúng thì tk nha
-3/7+15/26-(2/13-3/7)
= -3/7+15/26-2/13+-3/7
= -(3/7+ -3/7)+(15/26-2/13)
= 0 +11/26
= 11/26
mơm bạn nha