Tính nhanh:
a ) 2 3 + 5 7 + − 2 3 ; b ) − 1 4 + 5 8 + − 3 8 ; c ) − 6 13 + − 7 13 + 2 ; d ) − 5 27 + 1 3 + − 4 27
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a: \(=\dfrac{4}{5}\cdot\dfrac{7}{3}\cdot\dfrac{3}{7}\cdot\dfrac{5}{4}+2011=2011+1=2012\)
b: \(=\dfrac{1}{3}\cdot\dfrac{9}{7}\cdot\dfrac{7}{9}=\dfrac{1}{3}\)
có 2 cách làm mà mik làm 1 cách thôi nha !
A = (6 - 2/3 + 1/2) - (5 + 5/3 - 3/2) - (3 -7/3 + 5/2)
= ( 36/6 - 4/6 + 3/6 ) - ( 150/30 + 50/30 +45/30 ) - ( 18/6 - 14/6 + 15/6 )
= 35/6 - 155/30 - 19/6 = 35/6 - 19/6 - 155/30
= 16/6 - 155/30 = 80/30 - 155/30 = 75/30 = - 5/2
Hơi khó nhìn. Chúc hok tốt !
= 6 - (5+3) - (2/3 + 5/3 -7/3) + ( 1/2 + 3/2 -5/2 )
= 6 - 8 - 0 - 1/2
= -2 - 1/2
= -2/1/2
A = 6 - 2/3 + 1/2 - 5 - 5/3 + 3/2 - 3 + 7/3 - 5/2
A = ( 6 - 5 - 3 ) + ( -2/3 - 5/3 + 7/3 ) + ( 1/2 + 3/2 - 5/2 )
A = ( -2 ) + 0 + ( -1/2 )
A = ( -2 ) + ( -1/2 )
A = -5/2
c/
C = 1/100-1/100-1/99-1/99-1/98-1/98-1/97-..........-1/3-1/2-1/2-1/1
C = 1/100-1/100-1/1
C = 0-1/1
C = -1
a)
\(11\dfrac{3}{13}-\left(2\dfrac{4}{7}+5\dfrac{3}{13}\right)\)
\(=\dfrac{146}{13}-\left(\dfrac{18}{7}+\dfrac{68}{13}\right)\)
\(=\dfrac{146}{13}-\dfrac{18}{7}-\dfrac{68}{13}\)
\(=\left(\dfrac{146}{13}-\dfrac{68}{13}\right)-\dfrac{18}{7}\)
\(=6-\dfrac{18}{7}\)
\(=\dfrac{24}{7}\)
b)
\(\dfrac{2}{7}\times5\dfrac{1}{4}-\dfrac{2}{7}\times3\dfrac{1}{4}\)
\(=\dfrac{2}{7}\times\dfrac{21}{4}-\dfrac{2}{7}\times\dfrac{13}{4}\)
\(=\dfrac{2}{7}\times\left(\dfrac{21}{4}-\dfrac{13}{4}\right)\)
\(=\dfrac{2}{7}\times2\)
\(=\dfrac{4}{7}\)
\(a,11\dfrac{3}{13}-\left(2\dfrac{4}{7}+5\dfrac{3}{13}\right)\)
\(=\dfrac{146}{13}-\left(\dfrac{18}{7}+\dfrac{68}{13}\right)\)
\(=\dfrac{146}{13}-\dfrac{68}{13}-\dfrac{18}{7}\)
\(=6-\dfrac{18}{7}\)
\(=\dfrac{24}{7}\)
\(b,\dfrac{2}{7}\times5\dfrac{1}{4}-\dfrac{2}{7}\times3\dfrac{1}{4}\)
\(=\dfrac{2}{7}\times\dfrac{21}{4}-\dfrac{2}{7}\times\dfrac{13}{4}\)
\(=\dfrac{2}{7}\times\left(\dfrac{21}{4}-\dfrac{13}{4}\right)\)
\(=\dfrac{2}{7}\times2\)
\(=\dfrac{4}{7}\)
1)
a) \(...=4^4-225=256-225=31\)
b) \(...=8.9.5+120=360-120=240\)
c) \(...=3^4-3^3=81-27=54\)
d) \(...=7^2-1=49-1=48\)
2) a) \(...=2^6=64\)
b) \(...=3^{15}:3^{10}=3^5=243\)
c) \(...=3^3-3^3=0\)
d) \(...=6^3+4^5=216+1024=1240\)
`a,5 xx (-7)+(-2) xx (-5)`
`=5 xx (-7)+5 xx 2`
`= 5 xx (2-7)`
`=5 xx (-5)`
`=-25`
`b,5 xx (-9)+(-2) xx 3`
`=3 xx (-15)+3 xx (-2)`
`=3 xx (-15-2)`
`=3 xx (-17)`
`=-51`
`c,6 xx (-5)^2+3 xx (-15)`
`=2 xx 3 xx 25+3 xx (-15)`
`=3 xx 75-3 xx 15`
`=3 xx (75-15)`
`=3 xx 60`
`=180`
a) 5 7 .
b) 0.
c) 1.
d) 0.