Bài 1: Tính nhanh a)39.(250+87)+ 64.(240+97)
b)3.25.8+ 3.37.6+ 2.38.12
c)1+4+5+9+14+ …+60+97
d)2+6+18+54+ …+4374+13122
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18 * 23 +3 +45 * 6 +9 * 32 *2 =1263
425 *7*4 - 170 *60=1700
132 *9 +132 =1320
( 56* 27 +56 +35 ):62=\(\frac{1603}{62}\)
39 * ( 250 +87) +61 * ( 240 +97)=33700
Hk tốt!!! k cho mình nha!!@@
1) 12 x 2 x 25 + 29 x 25 + 59 x 25
= 24 x 25 + 29 x 25 + 59 x 25
= 25 x ( 24 + 29 + 59 )
= 25 x 112
= 2800
2) 25 x ( 231 + 69 ) + 72 x ( 231 + 69 )
= 25 x 300 + 72 x 300
= ( 25 + 72 ) x 300
= 29100
3)39 x ( 250 + 87 ) + 64 x ( 240 + 97 )
= 39 x 337 + 64 x 337
= ( 39 + 64 ) x 337
= 103 x 337
= 34711
tính nhanh
1) 12.2.25+29.25+59.25
2) 25.(231+69)+72.(231+69)
3) 39.(250+87)+64.(240+97)
4) 36.28+36.82+64.69+64.41
1) 12 x 2 x 25 + 29 x 25 + 59 x 25
= 24 x 25 + 29 x 25 + 59 x 25
= 25 x ( 24 + 29 + 59 )
= 25 x 112
= 2800
2) 25 x ( 231 + 69 ) + 72 x ( 231 + 69 )
= 25 x 300 + 72 x 300
= ( 25 + 72 ) x 300
= 29100
3)39 x ( 250 + 87 ) + 64 x ( 240 + 97 )
= 39 x 337 + 64 x 337
= ( 39 + 64 ) x 337
= 103 x 337
= 34711
36.(250+87)+64.(240+97)
=36.337 +64. 337
=(36+64) . 337
=100 .337
=33 700.
1) 12.2.25+29.25+59.25
=24.25+29.25+59.25
=25(24+29+59)
=25.112
=2800
2) 25.(231+69)+72.(231+69)
=25.300+72.300
=300(25+72)
=300.97
=29100
3) 39.(250+87)+64.(240+97)
=39.337+64.337
=337.(39+64)
=337.103
=34711
4) 36.28+36.82+64.69+64.41
=36.(28+82)+64.(69+41)
=36.110+64.110
=110(36+64)
=110.100
=11000
a) 36.(250+87)+64.(240+97)
= 36.( 240+10+87) + 64.(240+97)
= (240+97) . (36+64)
= 337.100
= 33700
b) 42.63+47.156-47.114
= 42.63 + 47.(156-114)
= 42.63 + 47.42
= 42.(63+47)
= 42.100
= 4200
k nha!
\(A=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{98.99}+\frac{1}{99.100}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+....+\frac{1}{98}-\frac{1}{99}+\frac{1}{99}-\frac{1}{100}\)
\(=1-\frac{1}{100}=\frac{99}{100}\)
\(B=\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{97.99}+\frac{2}{99.101}\)
\(=1-\frac{1}{3}+\frac{!}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{99}-\frac{1}{101}\)
\(=1-\frac{1}{101}=\frac{100}{101}\)
\(C=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+....+\frac{1}{1024}+\frac{1}{2048}\)
\(\Rightarrow\)\(2C=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+....+\frac{1}{512}+\frac{1}{1024}\)
\(\Rightarrow\)\(2C-C=\left(1+\frac{1}{2}+\frac{1}{4}+...+\frac{1}{1024}\right)-\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{2048}\right)\)
\(\Leftrightarrow\)\(C=1-\frac{1}{2048}=\frac{2047}{2048}\)
39.337+64.337=337.103=337.100+337.3=33700+1011=34711