b

d

vIETNAM

Gọi ba đơn vị kinh doanh là \(a;b;c\)

Theo đề bài :

\(\dfrac{a}{3}=\dfrac{b}{5}=\dfrac{c}{7}=a+b+c=300.000.000\)

Theo dãy số tính chất tỉ số bằng nhau ta có :

\(\dfrac{a}{3}=\dfrac{b}{5}=\dfrac{c}{7}=\dfrac{a+b+c}{3+5+7}=\dfrac{300}{15}=20\)

Từ đó ta suy ra :

\(\dfrac{a}{3}=20=a=20.3=60\)

\(\dfrac{b}{5}=20=b=20.5=100\)

\(\dfrac{c}{7}=20=c=20.7=140\)

\(\sqrt{\dfrac{2a}{3}.}\sqrt{\dfrac{3a}{8}=\sqrt{\dfrac{2a}{3}.\sqrt{\dfrac{3a}{8}}}=\sqrt{\dfrac{2.a}{3.8}}}\)

\(=\sqrt{\dfrac{\left(2.3\right)\left(a.a\right)}{3.8}=\sqrt{\dfrac{6a^2}{24}}}\)

\(=\sqrt{\dfrac{6a^2}{6.4}}=\sqrt{\dfrac{a^2}{4}=}=\sqrt{\dfrac{a^2}{2^2}}\)

\(=\sqrt{\dfrac{a}{2}}^2=\dfrac{a}{2}\)

Vì \(a>0\) nên \(\dfrac{a}{2}>0\)\(=\dfrac{a}{2}\)

b

a

is come

c

Câu 16 : C

Câu 17 : B

Câu 18 : A