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a) \(\left(1,2+0,8\right)\cdot2\cdot0,5=2\cdot1=1\)
b) \(\left(\frac{1}{2}+\frac{1}{3}\right)\cdot2\cdot\frac{3}{4}=\left(\frac{3}{6}+\frac{2}{6}\right)\cdot2\cdot\frac{3}{4}=\frac{5}{6}\cdot2\cdot\frac{3}{4}=\frac{5}{3}\cdot\frac{3}{4}=\frac{5}{4}\)
c) \(\left(1,5+1\right)\cdot2\cdot0,8=2,5\cdot2\cdot0,8=5\cdot0,8=4\)
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mink lm đc câu D thôi
D=1/2+1/4+1/8+...+1/256
D=1-1/2+1/2-1/4+1/4-1/8+1/8-1/16+....+1/128-1/256
D=1-1/256
D=255/256
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2 : x - 1,25 : x = 1,5
(2-1,25):x= 1,5
0,75 :x = 1,5
x= 0,75 : 1,5
x= 0,5
1,2 : x * 4 , 5 = 6
1,2 :x = 6 : 4,5
1,2 :x = 4/3
x= 1/2 : 4/3
x= 3/8
1,5 : 4,5 * x = 2,5
1/3x= 2,5
x= 2,5 : 1/3
x= 15/2
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A=126+72+163
A=397
B=1/6 x 1,25+0,25
B=1/6x5/4+1/4
B=5/24+1/4
B=11/24
c ko tìm đc
a) \(\frac{9}{4}-1,2+\frac{1}{4}=\frac{9}{4}+\frac{1}{4}-1,2=\frac{5}{2}-\frac{6}{5}=\frac{25-12}{10}=\frac{13}{10}\)
b) \(\frac{1}{3}+1,5-\frac{1}{4}=\frac{1}{3}+\frac{3}{2}-\frac{1}{4}=\frac{4+18-3}{12}=\frac{19}{12}\)