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- \(\frac{45}{6}=7,5\)
- 10:25\(\times6,8=0,4\times6,8\)vì 10:25=0,4
- 10:8\(\times3,2=\)1,25\(\times3,2\)vì 10:8=1,25
\(\frac{45}{6}\)= 7,5
10:25x6,8=2,72 10:8x3,2=4
0,4x6,8=2,72 1,25x3,2=4
Vậy 10:25x6,8=0,4x6,8 Vậy 10:8x3,2+1,25x3,2
cho mình nha

a = 2,45 x ( 46 + 54 ) + 8 x (0,5 + 0,75 )
= 2,45 x 100 + 8 x 1,25
= 245 + 10
= 255

( 1,25 - 0,25 x 5 ) x ( 1,2 x 1,2 x 1,3 x 1,4 x 1,5)
= ( 1,25 - 1,25) x ( 1,2 x 1,2 x 1,3 x 1,4 x 1,5)
= 0 x ( 1,2 x 1,2 x 1,3 x 1,4 x 1,5)
= 0
0,8 : [ \(\frac{4}{35}\)x 1,25 x ( 108% - \(\frac{2}{5}\)) : \(\frac{1}{2}\)]
Lm nhanh kết bạn tk nhá

=4/5:[4/35x5/4x(27/25-2/5):1/2]
=4/5:[1/7x17/25:1/2]
=4/5:[17/175:1/2]
=4/5:34/175
=4/5x175/34
=70/17

\(\frac{2x-4,36}{0,125}=0,25.42,9-11,7.0,25+0,25.0,8\)
\(\Leftrightarrow\frac{2x-4,36}{0,125}=0,25.\left(42,9-11.7+0,8\right)\)
\(\Leftrightarrow\frac{2x-4,36}{0,125}=0,25.32\)
\(\Leftrightarrow\frac{2x-4,36}{0,125}=8\)
\(\Leftrightarrow2x-4,36=1\)
\(\Leftrightarrow2x=5,36\)
\(\Leftrightarrow x=2,68\)
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) \(T=\frac{2009\cdot2010+2000}{2011\cdot2010-2020}\)
\(T=\frac{2009\cdot2010+2000}{2009\cdot2010+4020-2020}\)
\(T=\frac{2009\cdot2010+2000}{2009\cdot2010+2000}=1\)

e)\(\frac{0,1997+2,5\cdot12,5\cdot0,4\cdot0,08+8,003}{1,25\cdot2,5\cdot8\cdot4}=\frac{0,1997+1+8,003}{100}=\frac{2}{100}=\frac{1}{50}\)
g)\(\frac{\left(10,6524+0,3476\right)\cdot125\cdot0,4+8}{4\cdot0,1\cdot8\cdot0,25\cdot125}=\frac{11\cdot125\cdot0,4+8}{100}=\frac{558}{100}=5,58\)
9 x 1,25 x 3,2 x 8
= ( 9 x 3,2 ) x ( 8 x 1,25 )
= 28,8 x 10
= 288
9x1,25x3,2x8
=( 1,25 x 8) x9 x3,2
=10 x 9 x 3,2
=90 x 3,2 =288