TÍNH BẰNG CÁCH HỢP LÝ 7/21 + 125/75 + 14/21 + 25/175 GIÚP M NHANH NHÉ CẢM ƠN MN
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Đúng rồi đó, bằng 2.
Ta có: 7/21+3/21+14/21=7+3+14/21=24/21
125/175+25/175=125+25/175=150/175
Vì 24/21=8/7;150/175=6/7 nên 8/7+6/7=14/7=2
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a)54 : 33 + 6.52
= 54 : 27 + 6.25
= 2 + 150
= 152
b) 45.26 + 45.74 - 1500
= 45.(26 + 74) - 1500
= 45.100 - 1500
= 4500 - 1500
= 3000
c) 125 + 132 + (-125) + (-21)
= [125 + (-125)] + [132 + (-21)]
= 0 + 111
= 111
d) 11 - 13 + 15 - 17 + 19 - 21 + 23 - 25
= -2 + (-2) + (-2) + (-2)
= (-4) + (-2) + (-2)
= (-8)
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\(1\frac{4}{25}+\frac{7}{21}-\frac{4}{25}+0,5+\frac{14}{21}\)
\(=\left(1\frac{4}{25}-\frac{4}{25}\right)+\left(\frac{7}{21}+\frac{14}{21}\right)+0,5\)
\(=1+0+0,5\)
\(=1,5\)
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\(=\dfrac{75:25}{100:25}+\dfrac{18}{21}+\dfrac{19}{32}+\dfrac{1}{4}+\dfrac{3}{21}+\dfrac{13}{32}\\ =\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(\dfrac{18}{21}+\dfrac{3}{21}\right)+\left(\dfrac{19}{32}+\dfrac{13}{32}\right)\\ =1+1+1=3\)
7/21 + 125/75 + 14/21 + 25/175
= 1/3 + 5/3 + 2/3 + 1/7
= 8/3 + 1/7
= 59/21
\(\dfrac{7}{21}+\dfrac{125}{75}+\dfrac{14}{21}+\dfrac{25}{175}\)
\(=\left(\dfrac{7}{21}+\dfrac{14}{21}\right)+\dfrac{125}{75}+\dfrac{25}{175}\)
\(=\dfrac{21}{21}+\dfrac{5}{3}+\dfrac{1}{7}\)
\(=\dfrac{21}{21}+\dfrac{35}{21}+\dfrac{3}{21}\)
\(=\dfrac{59}{21}\)