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câu 1 và 2 k tính thuận tiện đc nhé bạn
câu 3 : = ( 28,35 + 42,65 + 1 ) : 0,125 = 72 : 0,125 = 9
7 - 1 = 0 <3 <3
1,25x10,8x0,8:0,9
=(1,25x0,8)x10,8:0,9
=1x10,8:0,9
=10,8:0,9
=12
0,64 x 0,04 x 25 : 0,8 + 0,5 x 0,112
=0,64x1:0,8+0,056
=0'64:0,8+0,056
=0,8+0,056
=0,856
28,35 : 0,125 + 42,65 :0,125 + 1 : 0,125
=28,35x8+42,65x8+1x8
=8x(28,35+42,65+1)
=8x72
=576
a, 1,25 x10,8 x 0,8 : 0,9
= (1,25 x 0,8) x (10,8 : 0,9)
= 1 x 12
= 12
b, 0,64 x 0,04 x25:0,8 + 0,5 x 0,112
= (0,64 : 0,8) x (0,04 x 25) + 0,5 x 0,112
= 0,8 x 1 + 0,056
= 0,8 + 0,056
= 0,856
tui cũng hỏi giống bạn nhưng không ai giai cho tui cả huhu
\(\frac{2x-4,36}{0,125}=0,25.42,9-11,7.0,25+0,25.0,8\)
\(\Leftrightarrow\frac{2x-4,36}{0,125}=0,25.\left(42,9-11.7+0,8\right)\)
\(\Leftrightarrow\frac{2x-4,36}{0,125}=0,25.32\)
\(\Leftrightarrow\frac{2x-4,36}{0,125}=8\)
\(\Leftrightarrow2x-4,36=1\)
\(\Leftrightarrow2x=5,36\)
\(\Leftrightarrow x=2,68\)
b) \(N=\frac{1}{1.5}+\frac{1}{5.10}+\frac{1}{10.15}+\frac{1}{15.20}+...+\frac{1}{2005.2010}\)
\(\Leftrightarrow N=\frac{1}{5}\left(1-\frac{1}{5}+\frac{1}{5}-\frac{1}{10}+\frac{1}{10}-\frac{1}{15}+\frac{1}{15}-\frac{1}{20}+...+\frac{1}{2005}-\frac{1}{2010}\right)\)
\(\Leftrightarrow N=\frac{1}{5}\left(1-\frac{1}{2010}\right)\)
\(\Leftrightarrow N=\frac{1}{5}.\frac{2009}{2010}=\frac{2009}{10050}\)
Bài 1:
a)\(\frac{2\cdot x-4,36}{0,125}=0,25\cdot42,9-11,7\cdot0,25+0,25\cdot0,8\)
\(\frac{2\cdot x-4,36}{0,125}=0,25\cdot\left(42,9-11,7+0,8\right)\)
\(\frac{2\cdot x-4,36}{0,125}=0,25\cdot32\)
\(\frac{2\cdot x-4,36}{0,125}=8\)
\(2\cdot x-4,36=8\cdot0,125\)
\(2\cdot x-4,36=1\)
\(2\cdot x=1+4,36\)
\(2\cdot x=5,36\)
\(x=\frac{5,36}{2}=2,68\)
b) \(N=\frac{1}{1\cdot5}+\frac{1}{5\cdot10}+\frac{1}{10\cdot15}+\frac{1}{15\cdot20}+...+\frac{1}{2005\cdot2010}\)
\(4N=\frac{4}{1\cdot5}+\frac{4}{5\cdot10}+\frac{4}{10\cdot15}+\frac{4}{15\cdot20}+...+\frac{4}{2005\cdot2010}\)
\(4N=1-\frac{1}{5}+\frac{1}{5}-\frac{1}{10}+\frac{1}{10}-\frac{1}{15}+\frac{1}{15}-\frac{1}{20}+...+\frac{1}{2005}-\frac{1}{2010}\)
\(4N=1-\frac{1}{2010}=\frac{2009}{2010}\)
\(N=\frac{2009}{2010}\div4=\frac{2009}{8040}\)
Bài 2:
a) ( x + 5,2 ) : 3,2 = 4,7 ( dư 0,5 )
\(x+5,2=4,7\cdot3,2+0,5\)
\(x+5,2=15,54\)
\(x=15,54-5,2=10,34\)
b)\(A=\frac{4047991-2010\cdot2009}{4050000-2011\cdot2009}\)
\(A=\frac{4047991-2010\cdot2009}{4050000-2009-2010\cdot2009}\)
\(A=\frac{4047991-2010\cdot2009}{4047991-2010\cdot2009}=1\)
Bài 3:
a) \(104,5\cdot x-14,1\cdot x+9,6\cdot x=25\)
\(x\cdot\left(104,5-14,1+9,6\right)=25\)
\(x\cdot100=25\)
\(x=\frac{25}{100}=\frac{1}{4}=0,25\)
b) \(T=\frac{2009\cdot2010+2000}{2011\cdot2010-2020}\)
\(T=\frac{2009\cdot2010+2000}{2009\cdot2010+4020-2020}\)
\(T=\frac{2009\cdot2010+2000}{2009\cdot2010+2000}=1\)
\(13,5\div0,5+13,5\div0,125.\)
\(=13,5\times2+13,5\times8\)
\(=13,5\times\left(2+8\right)\)
\(=13,5\times10\)
\(=135\)
13,5 : 0,5 + 13,5 : 0,125
= 13,5 : ( 0,5 + 0,125 )
= 13,5 : 0,625
= 21,6
a. 18,71 + 16,29 - ( 9,24 + 6,76 ) = 18,71 + 16,29 - 16 = 18,71 + 0,29 = 19
a,18,71-9,24+16,29-6,7
=(18,71-9,24)+(16,29-6,7)
=9,47+9,59
=19,06
b,25,75+24,36-35,75
=(35,75+25,75)+24,36
=61,5+24,36
=85,86
c,2,5 x 12,5 x 0,8 x 4
=(2,5 x 4) x (12,5 x 0,8)
=10 x 10
=100
d,0,125x0,6x8
=(0,125x8)x0,6
=1x0,6
=0,6
13 , 25 : 0 , 5 + 13 , 25 : 0 , 25 + 13 , 25 : 0 , 125
= 13 , 25 x 2 + 13 , 25 x 4 + 13 , 25 x 8
= 13 , 25 x ( 2 + 8 ) + 13 , 25 x 4
= 13 , 25 x 10 + 53
= 132 , 5 + 53
= 185 , 5
Chúc bạn học tốt !!!
\(13,25\div0,5+13,25\div0,25+13,25\div0,125\)
\(=\frac{53}{4}\div\frac{1}{2}+\frac{53}{4}\div\frac{1}{4}+\frac{53}{4}\div\frac{1}{8}\)
\(=\frac{53}{2}+53+106\)
\(=\frac{371}{2}\)
c, 28,35: 0,125 + 42,65: 0,125 + 1:0,125
= (28,35 + 42,65 + 1) : 0,125
= 72 : 0,125
= 72 x 8
= 576
a, 1,25 x 10,8 x 0,8:0,9
= (1,25 x 0,8) x (10,8 :0,9)
= 1 x 12
= 12