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c) \(\left(11+12+13+...+19\right).\left(6.8-48\right)=\left(11+12+13+...+19\right).\left(48-48\right)\)
\(=\left(11+12+13+...+19\right).0\)
\(=0\)
Hok "tuốt" nha^^
b) \(\left(500.9-250.18\right).\left(1+2+3+...+9\right)=\left(250.2.9-250.18\right).\left(1+2+...+9\right)\)
\(=\left(250.18-250.18\right).\left(1+2+3+...+9\right)\)
\(=0.\left(1+2+3+...+9\right)\)
\(=0\)
Hok tốt nha^^ (lần 2)
a, 4 x 113 x 8 - 32 x 13
= (4 x 8) x 113 - 32 x 13
= 32 x 113 - 32 x 13
= 32 x (113 - 13)
= 32 x 100 = 3200
b , 54 x 227 + 45 x 227 + 227
= 227 x (54+45+1)
= 227 x 100
= 22 700
c, ( 145 x 99 + 145 ) - ( 143 x101 - 143 )
= 145 x (99+1) - 143 x (101 - 1)
= 145 x 100 - 143 x 100
= 100 x (145 - 143)
= 100 x 2
= 200
a) \(4\times113\times8-32\times13\)
\(=4\times8\times113-32\times13\)
\(=32\times113-32\times13\)
\(=32\times\left(113-13\right)\)
\(=32\times100\)
\(=3200\)
b) \(54\times227+45\times227+227\)
\(=227\times\left(54+45+1\right)\)
\(=227\times100\)
\(=22700\)
c) \(\left(145\times99+145\right)-\left(143\times101-143\right)\)
\(=145\times\left(99+1\right)-143\left(101-1\right)\)
\(=145\times100-143\times100\)
\(=14500-14300\)
\(=200\)
a;
c; \(\dfrac{1}{10}\) + \(\dfrac{4}{20}\) + \(\dfrac{9}{30}\)+\(\dfrac{16}{40}+\dfrac{25}{50}+\dfrac{36}{60}+\dfrac{49}{70}+\dfrac{64}{80}+\dfrac{81}{90}\)
= \(\dfrac{1}{10}+\dfrac{2}{10}+\dfrac{3}{10}+\dfrac{4}{10}+\dfrac{5}{10}+\dfrac{6}{10}+\dfrac{7}{10}+\dfrac{8}{10}+\dfrac{9}{10}\)
= \(\dfrac{1+2+3+4+5+6+7+8+9}{10}\)
= \(\dfrac{\left(1+9\right)+\left(2+8\right)+\left(3+7\right)+\left(4+6\right)+5}{10}\)
= \(\dfrac{10+10+10+10+5}{10}\)
= \(\dfrac{\left(10+10+10+10\right)+5}{10}\)
= \(\dfrac{10\times4+5}{10}\)
= \(\dfrac{45}{10}\)
= \(\dfrac{9}{2}\)
Phần A hình như sai đầu bài , mình sửa lại và làm luôn nhé :
A = ( 2 + 4 + 6 + 8 .... + 100 ) x ( 142142 x 143 - 143143 x 142 )
A = ( 2 + 4 + 6 + 8 + ... + 100 ) x ( 142 x 1001 x 143 - 143 x 1001 x 142 )
A = ( 2 + 4 + 6 + 8 + .. + 100 ) x 0
A = 0
B = ( 630 - 315 x 2 ) : ( 1 + 2 + 3 + ... + 1000 )
B = ( 630 - 630 ) : ( 1 + 2 + 3 + ... + 100 )
B = 0 : ( 1 + 2 + 3 + ... + 100 )
B = 0
(129,3 - 60,8 ) x 5,2 + 143,8 = 500