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120+235+370+4140+5266+6475120+235+370+4140+5266+6475
=(120+370+4140)+(235+5266+6475)=(120+370+4140)+(235+5266+6475)
=17140+31350=17140+31350
=21100
A = \(\dfrac{1}{20}\) + \(\dfrac{2}{35}\) + \(\dfrac{3}{70}\) + \(\dfrac{4}{140}\) + \(\dfrac{5}{266}\) + \(\dfrac{6}{475}\)
A = \(\dfrac{1}{4\times5}\)+ \(\dfrac{2}{5\times7}\)+ \(\dfrac{3}{7\times10}\)+ \(\dfrac{4}{10\times14}\)+\(\dfrac{5}{14\times19}\)+\(\dfrac{6}{19\times25}\)
A = \(\dfrac{1}{4}\)-\(\dfrac{1}{5}\)+\(\dfrac{1}{5}\)-\(\dfrac{1}{7}\)+\(\dfrac{1}{7}\)-\(\dfrac{1}{10}\)+\(\dfrac{1}{10}\)+\(\dfrac{1}{10}\)-\(\dfrac{1}{14}\)+\(\dfrac{1}{14}\)-\(\dfrac{1}{19}\)+\(\dfrac{1}{19}\)-\(\dfrac{1}{25}\)
A = \(\dfrac{1}{4}\)-\(\dfrac{1}{25}\)
A = \(\dfrac{21}{100}\)
475 - ( 75 ) = 475 - 75 - 36
= 400 - 36
= 364
<=> (0,75+0,65+0,25+0,35)(0,25.2+0,25.3+0,25.5=2(0,25.10)=2.2,5=5
Đs: 5
[1.4+0.6]*[2.8+0.75+1.25]
2 * 4.8 =9.6
minh chac chan lun do minh tinh may tinh lai rui
\(=\left(\frac{75}{100}+\frac{65}{100}+\frac{1}{4}+\frac{35}{100}\right)\left(\frac{1}{4}.2+\frac{25}{100}.3+\frac{25}{100}.5\right)\)
\(=\left(\frac{3}{4}+\frac{13}{20}+\frac{1}{4}+\frac{7}{20}\right)\left(\frac{2}{4}+\frac{3}{4}+\frac{5}{4}\right)\)
\(=\left(1+1\right).\frac{10}{4}\)
\(=2.\frac{5}{2}\)
\(=5\)
35 . 34 + 35 . 38 + 65 . 75 + 65 . 45 + 35 . 34 =
= 35 . 34 + 35 . 38 + 35 . 34 + 65 . 75 + 65 . 45
= 35 . ( 34 + 38 + 34 ) + 65 . ( 75 + 45 )
= 35 . 110 + 65 . 110
= 110 . ( 35 + 65 )
= 110 . 100
= 11000
Hok tốt!!!!!!!!!!!!!
a) Tính bằng cách hợp lí nhất :
35 . 34 + 35 . 38 + 65 . 75 + 65 . 45 + 35 . 34
= 35 . 34 + 35 . 38 + 35 . 34 + 65 . 75 + 65 . 45
= 35 . ( 34 + 38 + 34 ) + 65 . ( 75 + 45 )
= 35 . 106 + 65 . 120
= 3710 + 7800
= 11510
3 . 25 . 8 + 4 . 37 . 6 + 2 . 38 . 12
= 3 . 8 . 25 + 4 . 6 . 37 + 2 . 12 . 38
= 24 . 25 + 24 . 37 + 24 . 38
= 24 . ( 25 + 37 + 38 )
= 24 . 100
= 2400
b) Tìm số tự nhiên x, biết :
( x - 5 ) ( x + 7 ) = 0
\(\Rightarrow\orbr{\begin{cases}x-5=0\\x+7=0\end{cases}\Rightarrow\orbr{\begin{cases}x=5\\x=-7\end{cases}}}.\)
Vậy .......
a) \(475-\left(75-36\right)\)
\(=475-75+36\)
\(=\left(475-75\right)+36\)
\(=400+36\)
\(=436\)
b)\(573-\left(73-24\right)\)
\(=573-73+24\)
\(=\left(573-73\right)+24\)
\(=500+24\)
\(=524\)
Like nha, thks
a)475-(75-36)
=475-75+36
=(475-75)+36
=400+36
=436
b)573-(73-24)
=573-73+24
=(573-73)+24
=500+24
=524
5(x - 35) - 75 = 475
=> 5x - 175 = 550
=> 5x = 725
=> x = 145
vậy)
5 . ( x - 35 ) - 75 = 475
5 . ( x - 35 ) = 475 - 75
5 . ( x - 35 ) = 400
x - 35 = 400 : 5
x - 35 = 80
x = 80 + 35
x = 115
Vậy x = 115