Câu 27: MSC(9;14)=9x14=126
Câu 28: B
Câu 29: D
Câu 30:
\(\dfrac{x+1}{18}=\dfrac{8}{16}=\dfrac{1}{2}=\dfrac{9}{18}\)
=>x+1=9
=>x=9-1=8
=>Chọn C
câu 31:
\(9=3^2;12=2^2\cdot3;18=3^2\cdot2\)
=>\(MSC\left(9;12;18\right)=BCNN\left(9;12;18\right)=2^2\cdot3^2=36\)