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a) x - 1845 = 115 x 2 - 25 x 3
x - 1845 = 230 - 75
x - 1845 = 155
x = 155 + 1845
\(b,230+35x4=x+\frac{700}{5}+30\)
230 + 140 = x + 140 + 30
370 = x + 170
x = 370 - 170
x = 200
a) x - 1845 = 115 x 2 - 25 x 3
x - 1845 = 230 - 75
x - 1845 = 155
x = 155 + 1845
x = 2000
Vậy x = 2000
b) 230 + 35 x 4 = x + 700 / 5+30
370 = x + 140 + 30
370 = x + 170
x = 370 - 170
x = 200
Vậy x = 200
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\(B=\frac{5}{30}+\frac{15}{90}+\frac{25}{150}+\frac{35}{210}+\frac{45}{270}\)
\(B=\frac{1}{6}+\frac{1}{6}+\frac{1}{6}+\frac{1}{6}+\frac{1}{6}=\frac{5}{6}\)
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\(Q=\frac{5}{30}+\frac{5}{30}+\frac{5}{30}+\frac{5}{30}+\frac{5}{30}\)
\(=\frac{5}{30}.5\)
\(=\frac{5}{6}\)
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a) (44 x 52 x 60) : (11 x 13 x 15)
= (44 : 11) x ( 52 : 13) x (60 : 15)
= 4 x 4 x 4 = 64
d) 1 + 6 + 11 + 16 + ... + 46 + 51
Ta có : 1 + 6 + 11 + 16 + ... + 46 + 51 ( có 11 số )
= (51 + 1) x 11 : 2 = 286
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5/2+13/6+25/12+41/20+61/30+85/42
=2+1/2+2+1/6+2+1/12+2+1/20+2+1/30+2+1/42
=12+(1/2+1/6+1/12+1/20+1/30+1/42)
=12+(1/1.2+1/2.3+1/3.4+1/4.5+1/5.6+1/6.7)
=12+(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7)
=12+1-1/7
=90/7
5/2+13/6+25/12+41/20+61/30+85/42
=2+1/2+2+1/6+2+1/12+2+1/20+2+1/30+2+1/42
=12+(1/2+1/6+1/12+1/20+1/30+1/42)
=12+(1/1.2+1/2.3+1/3.4+1/4.5+1/5.6+1/6.7)
=12+(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7)
=12+1-1/7
=90/7
5:25=0,2
30:90=0,3333...
700:630=1,1111...
5÷25=0,2
30÷90=0,333333...
700÷630=1,11111...