0,5x = 3/5

1/2x = 3/5 

     x = 3/5 : 1/2

     x = 3/5 x 2

     x = 6/5

X=6/5

\(A=\frac{7.6^{10}.2^{20}.3^6-2^{18}.6^{15}}{9.6^{19}.2^9-4.3^{17}.2^{26}}=\frac{7.\left(2.3\right)^{10}.2^{20}.3^6-2^{18}.\left(2.3\right)^{15}}{3^2.\left(2.3\right)^{19}.2^9-2^2.3^{17}.2^{26}}\)

                                                        \(=\frac{7.2^{10}.3^{10}.2^{20}.3^6-2^{18}.2^{15}.3^{15}}{3^2.2^{19}.3^{19}.2^9-2^2.3^{17}.2^{26}}\)

                                                         \(=\frac{7.2^{30}.3^{16}-2^{33}.3^{15}}{2^{28}.3^{21}-2^{28}.3^{17}}\)

                                                             \(=\frac{2^{30}.3^{15}.\left(7.3-2^3\right)}{2^{28}.3^{17}.\left(3^4-1\right)}\)

                                                              \(=\frac{2^2.13}{3^2.80}=\frac{4.13}{9.80}=\frac{13}{180}\)

\(A=\frac{7\cdot2^{10}\cdot3^{10}\cdot2^{20}\cdot3^6-2^{18}\cdot2^{15}\cdot3^{15}}{3^2\cdot3^{19}\cdot2^{19}\cdot2^9-2^2\cdot3^{17}\cdot2^{26}}=\frac{7\cdot2^{30}\cdot3^{16}-2^{33}\cdot3^{15}}{3^{21}\cdot2^{28}-2^{28}\cdot3^{17}}\)

\(A=\frac{2^{30}\cdot3^{15}\left(7\cdot3-2^3\right)}{2^{28}\cdot3^{17}\left(3^4-1\right)}=\frac{2^{30}\cdot3^{15}\cdot13}{2^{28}\cdot3^{17}\cdot2^4\cdot5}=\frac{13}{2^2\cdot3^2\cdot5}=\frac{13}{180}\)

Chị ko bt có sai ko nx nếu có sai thông cảm chị nha

^-^

Ta có \(9^{x-1}=\frac{1}{9}\)

\(\Leftrightarrow9^x.9^{-1}=\frac{1}{9}\)

\(\Leftrightarrow9^x=9^{-1}:9^{-1}\)

\(\Leftrightarrow9^x=1\)

\(\Leftrightarrow x=0\)

Ta có :\(9^{x-1}=\frac{1}{9}=\frac{9^0}{9}=9^0:9^1=9^{-1}\)

=> x - 1 = -1 => x= 0

của Đinh Tiên Hoàng Ninh Bình thì càng tốt 

bạn lên mạng tìm nhé chứ giờ viết ra cũng mệt lắm

mk nek..................................................

Hihi

Mk tên là trân 

năm sinh :2k7

giới :nữ

ny:của bạn thì L tớ thì ko nói ^.^

lớp :6/6

CHÚNG TA CÙNG TRƯỜNG

Viết 1 bưu thiếp gửi bạn về kì nghỉ của mình:

Hi, Ha!

We are having a great time in Ha Long Bay. It is in Quang Ninh province. The weather is perfect and we're spendinh our days on the beach. Ha Long Bay has many caves and islands. Tuan Chau is the biggest island in Ha Long Bay. I am going to take a boat ride around the islands tomorrow. There I can enjoy great Vietnamese seafood. It's so delicious. I am watching traditional dance and joining lots of exciting activities. The people here are friendly and open. 

I look forward to hearing from you.

Love,

Huyen.

Trò chơi thể thao yêu thích nhất

My favourite sport is football. Football is the most popular sport in the world. This game needs 22 players to play, each team has 11 people. The rule of this game is kich the ball to another team's golf that can't use hands, just use head and feet. Which team violation will fined. Who violation too much will be out. Football is a sport that promotes solidarity, it's helps us healthier and stronger. I love football and I will play it everyday.

\(A=\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+\frac{1}{6^2}+...+\frac{1}{100^2}\)

\(A< \frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+...+\frac{1}{99.100}\)

\(A< \frac{3-2}{2.3}+\frac{4-3}{3.4}+\frac{5-4}{4.5}+\frac{6-5}{5.6}+...+\frac{100-99}{99.100}\)

\(A< \frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{99}-\frac{1}{100}\)

\(A< \frac{1}{2}-\frac{1}{100}=\frac{49}{100}=\left(\frac{7}{10}\right)^2\)

Ta có \(\frac{25}{36}=\left(\frac{5}{6}\right)^2\)

Ta thấy \(\frac{5}{6}=\frac{25}{30}>\frac{7}{10}=\frac{21}{30}\Rightarrow\left(\frac{7}{10}\right)^2< \left(\frac{5}{6}\right)^2\Rightarrow A< \left(\frac{7}{10}\right)^2< \left(\frac{5}{6}\right)^2=\frac{25}{36}\)