Bài 1:
a: \(73\cdot142+73\cdot258\)
\(=73\left(142+258\right)\)
\(=73\cdot400=29200\)
b: \(3\cdot3^2-5^6:5^4+\left(2021-2020\right)^{200}\)
\(=3^3-5^2+1\)
=27-25+1
=28-25
=3
c: \(420:\left\lbrack219-\left(17-14\right)^2\right\rbrack\)
\(=420:\left\lbrack219-3^2\right\rbrack\)
=420:(219-9)
=420:210
=2
Bài 2:
a: 105-(x+52)=45
=>x+52=105-45=60
=>x=60-52
=>x=8
b: \(12\left(x-9\right)=132\)
=>x-9=132/12=11
=>x=11+9
=>x=20
c: \(169-5^{x+2}=144\)
=>\(5^{x+2}=169-144=25=5^2\)
=>x+2=2
=>x=0
d: \(24=2^3\cdot3;36=2^2\cdot3^2;60=2^2\cdot3\cdot5\)
=>BCNN(24;36;60)=\(2^3\cdot3^2\cdot5=8\cdot9\cdot5=360\)
x⋮24; x⋮36; x⋮60
=>x∈BC(24;36;60)
=>x∈B(360)
mà x là số tự nhiên nhỏ nhất khác 0
nên x=360
