Câu 12: A
Bài 1:
a: \(4\cdot5^2-64:2^3=4\cdot25-64:8=100-8=92\)
b: \(24\cdot\left[119-\left(23-6\right)\right]\)
\(=24\cdot\left[119-17\right]\)
\(=24\cdot102=2448\)
Câu 2:
a: 2(x+25)=60
=>\(x+25=\dfrac{60}{2}=30\)
=>x=30-25=5
b: \(12x-33=3^{2020}:3^{2019}\)
=>12x-33=3
=>12x=33+3=36
=>\(x=\dfrac{36}{12}=3\)
Câu 4:
\(72=2^3\cdot3^2;90=2\cdot3^2\cdot5\)
=>\(ƯCLN\left(72;90\right)=2\cdot3^2=18\)
=>\(ƯC\left(72;90\right)=Ư\left(18\right)=\left\{1;-1;2;-2;3;-3;6;-6;9;-9;18;-18\right\}\)
Câu 12: A
Bài 1:
a: \(4\cdot5^2-64:2^3=4\cdot25-64:8=100-8=92\)
b: \(24\cdot\left[119-\left(23-6\right)\right]\)
\(=24\cdot\left[119-17\right]\)
\(=24\cdot102=2448\)
Câu 2:
a: 2(x+25)=60
=>\(x+25=\dfrac{60}{2}=30\)
=>x=30-25=5
b: \(12x-33=3^{2020}:3^{2019}\)
=>12x-33=3
=>12x=33+3=36
=>\(x=\dfrac{36}{12}=3\)
Câu 4:
\(72=2^3\cdot3^2;90=2\cdot3^2\cdot5\)
=>\(ƯCLN\left(72;90\right)=2\cdot3^2=18\)
=>\(ƯC\left(72;90\right)=Ư\left(18\right)=\left\{1;-1;2;-2;3;-3;6;-6;9;-9;18;-18\right\}\)
