27.64 < x < 28.46
x = ........
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Tính nhanh
a) 27.26 + 27.64
b) 25.37 + 25.63 - 150
c) 425.7.4 = 170.60
d) 0.9.14 + 6.17.12 + 19.4.18
a, 27.26+27.64
=27.(26+64)
=27.90
=2430
b,25.37+25.63-150
=25.(37+63)-150
=25.110-150
=2750-150
=2600
c,425.7.4=170.60
=1700.7=170.10.6
=1700.7-1700.6
=1700.(7-6)
=1700
d,0.9.14+6.17.12+19.4.18
=0+6.17.12+19.4.18
=6.3.4.17+19.4.18
=18.4.17+19.4.18
=18.4.(17+19)
=72.36=2592
a) \(227+50+23=\left(227+23\right)+50=250+50=300\)
b) \(135+360+65+40=\left(135+65\right)+\left(360+40\right)=200+400=600\)
c) \(1+2+3+4+5+...+97+98+99+100\)
\(=\left(100+1\right)+\left(99+2\right)+...+\left(50+51\right)\)
\(=101+101+101+...+101\)
\(=101\cdot50\)
\(\Leftrightarrow5050\)
d) \(115\cdot13-13\cdot15=13\cdot\left(115-15\right)=13\cdot100=1300\)
e) \(50-49+48-47+...+4-3+2-1\)
\(=\left(50-49\right)+\left(48-47\right)+...+\left(2-1\right)\)
\(=1+1+1+1+..+1\)
\(=1\cdot25\)
\(=25\)
f) \(30\cdot40\cdot50\cdot60=10\cdot3+10\cdot4+10\cdot5+10\cdot6\)
\(=10\cdot10\cdot10\cdot10\cdot3\cdot4\cdot5\cdot6\)
\(=10000\cdot360\)
\(=3600000\)
g) \(27\cdot36+27\cdot64=27\cdot\left(36+64\right)=27\cdot100=2700\)
h) \(5\cdot2^2-18:3=5\cdot4-18:3=20-6=14\)
i) \(13\cdot17-256:16+14:7-2021^0\)
\(=13\cdot17-4^4:4^2+2-1\)
\(=13\cdot17-16+2-1\)
\(=13\cdot17-17\)
\(=17\cdot\left(13-1\right)\)
\(=204\)
j) \(7^2-36:3=49-12=37\)
a) x(1-1)=1
<=>x.0=1
<=>0=1 ( vô nghiệm)
b)x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x= 54x
a, x.25=380125
x=380125:25
x=15205
b, (45,2+45.2)+2+x=2525255
45.2.2
45 . 2 + 2 + x + 45 . 2 = 2525255
=> 2 . (45 + 45 + 1) + x = 2525255
=> 182 + x = 2525255
=> x = 2525073
x = 28 bạn nhé