Bài 3:
a: 3x-2=19
=>3x=19+2=21
=>\(x=\frac{21}{3}=7\)
b: 70-5(x-3)=45
=>5(x-3)=70-45=25
=>\(x-3=\frac{25}{5}=5\)
=>x=5+3
=>x=8
c: (7x-15):3=9
=>\(7x-15=3\cdot9=27\)
=>7x=27+15=42
=>\(x=\frac{42}{7}=6\)
d: \(71+\left(x-16:2^2\right)=75\)
=>x-16:4=75-71=4
=>x-4=4
=>x=4+4
=>x=8
e: [43-(56-x)]*12=384
=>(43-56+x)=384/12=32
=>x-13=32
=>x=32+13
=>x=45
f: \(3^{x}\cdot2+15=33\)
=>\(3^{x}\cdot2=33-15=18\)
=>\(3^{x}=\frac{18}{2}=9=3^2\)
=>x=2
Bài 2:
a: \(50+\left\lbrack65-\left(9-4\right)^2\right\rbrack\)
=50+[65-25]
=50+40
=90
b: \(80+\left\lbrack37-\left(3^2+2^3\right)\right\rbrack\)
=80+[37-(9+8)]
=80+(37-17)
=80+20
=100
c: \(3^7:3^3+2^3:4\)
\(=3^4+8:4\)
=81+2
=83
d; \(2^2\cdot85+40\cdot2^2-2^3\cdot12\)
\(=2^2\left(85+40\right)-2^3\cdot12\)
\(=2^2\cdot125-8\cdot12\)
=500-96
=404
e: \(\left\lbrack\left(36-22\right)^2-\left(64-52\right)^2\right\rbrack\cdot36-872\)
\(=\left\lbrack\left(36-22-64+52\right)\left(36-22+64-52\right)\right\rbrack\cdot36-872\)
\(=\left\lbrack2\cdot26\right\rbrack\cdot36-872=72\cdot26-872=1000\)
f: \(5^7:5^5+2^2\cdot2^4-2022^0\)
\(=5^2+2^6-1\)
=25+64-1
=24+64
=88
