ta có : \(\frac{18\cdot34+\left(-18\right)\cdot124}{\left(-36\right)\cdot17+9\cdot\left(-52\right)}\) =\(\frac{18\cdot34-18\cdot124}{9\cdot\left(-4\right)\cdot17+9\cdot-52}\)

            =\(\frac{18\cdot\left(34-124\right)}{9\cdot\left(-68+-52\right)}\)

            =\(\frac{18\cdot\left(-90\right)}{9\cdot\left(-120\right)}=\frac{3}{2}\)

c

C

\(C.\dfrac{2}{3}\)

a)\(\frac{16}{20}=\frac{4}{5};\frac{9}{15}=\frac{3}{5}\)

Vì 4>3\(\Rightarrow\frac{4}{5}>\frac{3}{5}\) hay \(\frac{16}{20}>\frac{9}{15}\)

Vậy \(\frac{16}{20}>\frac{9}{15}\)

b) \(\frac{6}{8}=\frac{3}{4};\frac{3}{12}=\frac{1}{4}\)

Vì 3>1 \(\Rightarrow\frac{3}{4}>\frac{1}{4}\) hay \(\frac{6}{8}=\frac{3}{12}\)

Vậy \(\frac{6}{8}=\frac{3}{12}\)

c) \(\frac{15}{25}=\frac{3}{5};\frac{36}{45}=\frac{4}{5}\)

Vì 3<4 \(\Rightarrow\frac{3}{5}<\frac{4}{5}\) hay \(\frac{15}{25}<\frac{36}{45}\)

Vậy \(\frac{15}{25}<\frac{36}{45}\)

Neu ban nao dung thi minh tich cho nhe

_{minh khong biet dap an cua cau hoi nay} 

\(\dfrac{-8^3\cdot6^4}{18^{12}}=\dfrac{2^3\cdot4^3\cdot2^2\cdot3^2}{2^{12}\cdot3^{12}\cdot3^{12}}\)

\(=\dfrac{2^5\cdot\left(2^2\right)^3\cdot3^2}{2^{12}\cdot3^{12}\cdot3^{12}}=\dfrac{2^6}{2^7\cdot3^{10}\cdot3^{12}}\)

\(=\dfrac{1}{2\cdot3^{22}}\)

a = \(\frac{-8^3.6^4}{18^{12}}\)

   = \(\frac{-2^9.2^4.3^4}{2^{12}.3^{24}}\)

   = \(\frac{-2^{13}.3^4}{2^{12}.3^{24}}\)

   = \(\frac{-2}{3^{20}}\)

Hk tốt

84/98 bạn nhé

hiêụ giữa phân số mới và phân cũ là

6/7-36/49=6/49

mẫu số là

12x49/6=98

tử số là

98/7x6=84

phân số đó là 84/98

Đ/s 84/98

\(\frac{9^9\cdot225^5\cdot8^7}{18^{12}\cdot625^3\cdot24^3}=\frac{9^9\cdot\left(\left(3\cdot5\right)^2\right)^5\cdot8^7}{\left(9\cdot2\right)^{12}\cdot\left(\left(5^2\right)^2\right)^3\cdot\left(8\cdot3\right)^3}\)

\(=\frac{1}{9^3\cdot2^{12}}\cdot\frac{9^5\cdot5^{10}}{5^{12}}\cdot\frac{8^7}{8^3\cdot3^3}\)

\(=\frac{9^2\cdot8^4}{2^{12}\cdot5^2\cdot3^3}\)

\(=\frac{9\cdot\left(2^4\right)^3}{\left(2^4\right)^3\cdot5^2}\)

\(=\frac{9}{25}\)