\(\left[19\left(4\cdot2^3+18\right)-9\cdot50\right]:5^2\\ =\left[19\left(4\cdot8+18\right)-450\right]:25\\ =\left[19\cdot50-450\right]:25\\ =\left[950-450\right]:25\\ =500:25\\ =20\)

Ta có:

\(\dfrac{4}{5}\) thế kỉ \(=80\) năm

Cây đo đó trồng năm là:

\(2024-80=1944\left(năm\right)\)

\(x+62^2=x+3844\)

\(\rightarrow\) Đề chưa đầy đủ ạ

\(\dfrac{a+13}{a+11}=\dfrac{a+11+2}{a+11}=1+\dfrac{2}{a+11}\)

\(\dfrac{a+2023}{a+2021}=\dfrac{a+2021+2}{a+2021}=1+\dfrac{2}{a+2021}\)

Vì: \(\dfrac{2}{a+11}>\dfrac{2}{a+2021}\) nên \(\dfrac{a+13}{a+11}>\dfrac{a+2023}{a+2021}\)

\(20,46cm^2=20,46:10000=0,002046m^2\)

Vì: \(1cm^2=\dfrac{1}{10000}m^2=0,0001m^2\)

Sửa đề:

\(\left(7^5+7^9\right)\cdot\left(5^4+5^6\right)\cdot\left(3^3\cdot3-9^2\right)\\ =\left(7^5+7^9\right)\cdot\left(5^4+5^6\right)\cdot\left(3^4-3^4\right)\\ =\left(7^5+7^9\right)\cdot\left(5^4+5^6\right)\cdot0\\ =0\)

Ta có:

\(\dfrac{3}{12}=\dfrac{3}{12}=1\)

\(\dfrac{3}{13}< \dfrac{3}{12}\)

\(\dfrac{3}{14}< \dfrac{3}{12}\)

\(\dfrac{3}{15}< \dfrac{3}{12}\)

\(\dfrac{3}{16}< \dfrac{3}{12}\)

\(\dfrac{3}{17}< \dfrac{3}{12}\)

\(\dfrac{3}{18}< \dfrac{3}{12}\)

\(\rightarrow\dfrac{3}{12}+\dfrac{3}{13}+\dfrac{3}{14}+\dfrac{3}{15}+\dfrac{3}{16}+\dfrac{3}{17}+\dfrac{3}{18}< \dfrac{3}{12}+\dfrac{3}{12}+\dfrac{3}{12}+\dfrac{3}{12}+\dfrac{3}{12}+\dfrac{3}{12}+\dfrac{3}{12}=\dfrac{3+3+3+3+3+3+3}{12}=\dfrac{21}{12}=\dfrac{7}{4}\)Vậy: \(\dfrac{3}{12}+\dfrac{3}{13}+\dfrac{3}{14}+\dfrac{3}{15}+\dfrac{3}{16}+\dfrac{3}{17}+\dfrac{3}{18}< \dfrac{7}{4}\)

\(\dfrac{22}{25}-\dfrac{4}{5}=\dfrac{22}{25}-\dfrac{20}{25}=\dfrac{22-20}{25}=\dfrac{2}{25}\)

Bạn chú ý đăng linh tinh nha!

\(9^{23}:\left(0,375\right)^{46}\\ =9^{23}:\left(0,375\right)^{23}:\left(0,375\right)^{23}\\ =\left(9:0,375:0,375\right)^{23}\\ =64^{23}\)