mấy bn giúp mình nhé:
1) tính thuận tiện:
a) 45.32+45.66+45+45
b) (2013+2014+2015)x(30.12-18.20)
c) (12+12+12.88)x45+12.10
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\(\frac{12}{15}\times\frac{22}{47}+\frac{25}{47}:\frac{15}{12}\)
\(\frac{12}{15}\times\frac{22}{47}+\frac{25}{47}\times\frac{12}{15}\)
\(=\frac{12}{15}\times\left(\frac{22}{47}+\frac{25}{47}\right)\)
\(=\frac{12}{15}\times\frac{22+25}{47}\)
\(=\frac{12}{15}\times1=\frac{12}{15}\)
a) 20,8 x 45 + 0,37 x 15 + 20,8 x 55 x 0,63
= 20,8 x ( 45 + 55 x 0,63 ) + 0,37 x 15
= 20,8 x ( 45 + 34,65 ) + 5,55
= 20,8 x 79,65 + 5,55
= 1656,72 + 5,55
= 1662,27
b) ( 2013 x 2014 + 2014 x 2015 + 2015 x 2016 ) x ( 1 + 1/3 - 1 và 1/3 )
= ( 2013 x 2014 + 2014 x 2015 + 2015 x 2016 ) x [( 1 - 1 ) + ( 1/3 - 1/3 ) ]
= ( 2013 x 2014 + 2014 x 2015 + 2015 x 2016 ) x 0
= 0
( 2013 x 2014 + 2014 x 2015 + 2015 x 2016) x ( 1 + 1/3 - 4/3)
=( 2013 x 2014 + 2014 x 2015 + 2015 x 2016) x ( 4/3 - 4/3)
=( 2013 x 2014 + 2014 x 2015 + 2015 x 2016) x 0
=0
Ta có: \(\left(2013\cdot2014+2014\cdot2015+2015\cdot2016\right)\left(1+\dfrac{1}{3}-\dfrac{4}{3}\right)\)
\(=\left(2013\cdot2014+2014\cdot2015+2015\cdot2016\right)\left(\dfrac{3}{3}+\dfrac{1}{3}-\dfrac{4}{3}\right)\)
=0
a) 0,25x3/4-0,25x0,25+0,25x1/2
=0,25x(3/4-0,25+1/2)
=0,25x1
=0,25
b) 5,68x8+56,8x0,1+56,8:10
=5,68x8+5,68+5,68
=5,68x(8+1+1)
=5,68x10
=56,8
a)45x32+45x66+45+45
=45x(32+66+1+1)
=45x100
=4500
a.45.32+45.66+45.2
= 45.(32+66+2)
=45.100=4500
b.(2013+2014+2015).(20+10).12-18.20
=(2013+2014+2015).(30.12-(12+6).20)
=(2013+2014+2015).(30*12-12.20-6.20)
=(2013+2014+2015).(12.(30-20)-6.20)
=(2013+2014+2015).(12.10-6.20)
=(2013+2014+2015).(120-120)
=(2013+2014+2015).0
=0
c.(12+12+12.88).45+12.12
=(12.(1+1+88)).45+12.10
=12.90.45+120
=12.9.10.5.9+120
=1080.5.9+120
=5400.9+120
=48600+120
=48720
nho k cho to nhe