a) 18/24 + 35/-21 - 1/2
b) -2/3 - 3/-4 + 5/-6
c) ( 3/4 + -7/2) . ( 10/11 + 2/22)
d) ( 7/3 - -7/2) : ( -25/6 . 1/5)
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a; \(\dfrac{9}{4}\) - \(\dfrac{-11}{4}\)
= \(\dfrac{9}{4}\) + \(\dfrac{11}{4}\)
= \(\dfrac{20}{4}\)
= 5
b; \(\dfrac{7}{8}\) - \(\dfrac{3}{-8}\) - \(\dfrac{1}{8}\)
= \(\dfrac{7}{8}\) + \(\dfrac{3}{8}\) - \(\dfrac{1}{8}\)
= \(\dfrac{7+3-1}{8}\)
= \(\dfrac{9}{8}\)
c; \(\dfrac{-5}{21}\) - \(\dfrac{25}{21}\) - \(\dfrac{-1}{21}\)
= \(\dfrac{-5}{21}\) - \(\dfrac{25}{21}\) + \(\dfrac{1}{21}\)
= \(\dfrac{-5-25+1}{21}\)
= \(\dfrac{-29}{21}\)
2/3 + 3/4=17/12
9/4 + 3/5=57/20
5/24 + 1/4=11/24
3/15 - 5/35=2/35 18/27 - 2/6=1/3 37/12 - 3=1/12
11/9 x 3/22=1/6 7/13 x 13/7=1 4 x6/7=24/7
2/5 : 3/10=4/3 3/8 : 9/4=1/6 8/21 : 4/7=2/3
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15 +16 +17 +18 + 19 + 20 + 21 + 22 + 23 + 24 + 25=325
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15 +16 +17 +18 + 19 + 20 + 21 + 22 + 23 + 24 + 25 = 325
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37
=(1+37)x37:2
=703
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26=351
Số số hạng của dãy số là:
(26-1):1+1=26 (số)
Tổng của dãy số là:
(26+1)*26:2=351
Đáp số 351
a: \(\dfrac{18}{24}+\dfrac{35}{-21}-\dfrac{1}{2}\)
\(=\dfrac{3}{4}-\dfrac{5}{3}-\dfrac{1}{2}\)
\(=\dfrac{9-20-6}{12}=\dfrac{-17}{12}\)
b: \(\dfrac{-2}{3}-\dfrac{3}{-4}+\dfrac{5}{-6}\)
\(=-\dfrac{2}{3}+\dfrac{3}{4}-\dfrac{5}{6}\)
\(=\dfrac{-8+9-10}{12}=\dfrac{-9}{12}=\dfrac{-3}{4}\)
c: \(\left(\dfrac{3}{4}+\dfrac{-7}{2}\right)\cdot\left(\dfrac{10}{11}+\dfrac{2}{22}\right)\)
\(=\left(\dfrac{3}{4}-\dfrac{14}{4}\right)\cdot\left(\dfrac{10}{11}+\dfrac{1}{11}\right)\)
\(=-\dfrac{11}{4}\cdot1=-\dfrac{11}{4}\)
d: \(\left(\dfrac{7}{3}-\dfrac{-7}{2}\right):\left(-\dfrac{25}{6}\cdot\dfrac{1}{5}\right)\)
\(=\left(\dfrac{7}{3}+\dfrac{7}{2}\right):\dfrac{-5}{6}\)
\(=\dfrac{35}{6}\cdot\dfrac{6}{-5}=\dfrac{35}{-5}=-7\)
a) \(\dfrac{18}{24}+\dfrac{35}{-21}-\dfrac{1}{2}\)
\(=\dfrac{3}{4}-\dfrac{5}{3}-\dfrac{1}{2}\)
\(=\dfrac{9}{12}-\dfrac{20}{12}-\dfrac{6}{12}\)
\(=\dfrac{-17}{12}\)
b) \(\dfrac{-2}{3}-\dfrac{3}{-4}+\dfrac{5}{-6}\)
\(=\dfrac{-8}{12}+\dfrac{9}{12}-\dfrac{10}{12}\)
\(=\dfrac{-9}{12}\)
\(=\dfrac{-3}{4}\)
c) \(\left(\dfrac{3}{4}+\dfrac{-7}{2}\right).\left(\dfrac{10}{11}+\dfrac{2}{22}\right)\)
\(=\dfrac{-11}{4}.1\)
\(=\dfrac{-11}{4}\)
d) \(\left(\dfrac{7}{3}-\dfrac{-7}{2}\right):\left(-\dfrac{25}{6}.\dfrac{1}{5}\right)\)
\(=\dfrac{35}{6}:\dfrac{-5}{6}\)
\(=-7\)