1.
\(\left(\frac{3}{1\times3}+\frac{3}{3\times5}+\frac{3}{5\times7}+...+\frac{3}{97\times99}\right)-x:\frac{3}{2}=\frac{7}{3}\\ \left(\frac{2}{1\times3}+\frac{2}{3\times5}+\frac{2}{5\times7}+...+\frac{2}{97\times99}\right):\frac{3}{2}-x:\frac{3}{2}=\frac{7}{3}\\\left[\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{97}-\frac{1}{99}\right)-x\right]:\frac{3}{2}=\frac{7}{3}\\ \left(1-\frac{1}{99}\right)-x=\frac{7}{3}\times\frac{3}{2}\\ \frac{98}{99}-x=\frac{7}{2}\\ x=\frac{98}{99}-\frac{7}{2}=\frac{-497}{198}\)

2.\(\frac{x}{y}=\frac{4}{3}\Rightarrow\hept{\begin{cases}x=4a\\y=3a\\x-y=4a-3a=a\end{cases}}\\ \left(x-y\right)^{2015}=5^{2015}\Rightarrow x-y=5\\ \Rightarrow a=5\Rightarrow\hept{\begin{cases}x=4\times5=20\\y=3\times5=15\end{cases}}\)

1.

Ta có: \(5^{x+1}\cdot7^y=175^x\)

\(\Leftrightarrow5^{x+1}\cdot7^y=\left(25\right)^x\cdot7^x\)

\(\Leftrightarrow5^{x+1}\cdot7^y=5^{2x}\cdot7^x\)

Vì x,y là STN và ( 5,7 ) = 1

=> \(\hept{\begin{cases}5^{x+1}=5^{2x}\\7^y=7^x\end{cases}}\Rightarrow\hept{\begin{cases}x+1=2x\\x=y\end{cases}}\Leftrightarrow x=y=1\)

Vậy x = y = 1

ủa hôm qua nhìu bạn chỉ lắm mà

\(1) 420+65.4=(x+175):5+30\)

\(\implies 420+260=(x+175):5+30\)

\(\implies 680=(x+175):5+30\)

\(\implies 650=(x+175):5\)

\(\implies 650.5-175=x\)

\(\implies 3075=x\)

\(2)x-4867=(175.2050.70):25+23\)

\(\implies x-4867=1004500+23\)

\(\implies x-4867=1004523\)

\(\implies x=1009390\)

\(3) 134-[(96-7x):4-2]=126\)

\(\implies (96-7x):4-2=8\)

\(\implies(96-7x):4=10\)

\(\implies 96-7x=40\)

\(\implies 7x=56\)

\(\implies x=8\)

\(4) 4-\{100-[(100-5x):8-5]:10\}:25=0\)

\(\implies 4-\{100-[(100-5x):8-5]:10\}=0\)

\(\implies 100-[(100-5x):8-5]:10=4\)

\(\implies 100-[(100-5x):8-5]=40\)

\(\implies (100-5x):8-5=60\)

\(\implies (100-5x):8=65\)

\(\implies 100-5x=520\)

\(\implies 5x=-420\)

\(\implies x=-84\)

~ Hok tốt a~

ai nua cac ban

ban nao biet thi minh h

a) ( 1 + 3 + 5 + ....+ 97 + 99 ) - 2 x X = 500 

Áp dụng công thức tính dãy số ta có :

\(1+3+5+...+99=\frac{\left[\left(99-1\right):2+1\right].\left(99+1\right)}{2}=50.100:2=50.50=2500\)

=> 2500 - 2X = 500

=> 2X = 2500 - 500 = 2000

=> X = 2000 : 2 = 1000

a) Ta có : 1 + 3 + 5 + ..... + 97 + 99 

Số số hạng trên là :

 ( 99 - 1 ) : 2 + 1 = 50 số hạng :

 Tổng trên là :

 ( 99 - 1 ) x 50 : 2 = 2450 

Thế vào câu a ta được :

 2450 - 2x = 500

=> 2x = 1950

=> x = 975

b)  X - 1234 = ( 175 x 2 - 50 x 7 ) : 23 + 23 

=> X - 1234 = (350 - 350) : 23 + 23

=> X - 1234 = 0 : 23 + 23

=> X - 1234 = 0 + 23 = 23

=> X = 23 + 1234

=> X = 1257

`7 xx x + 5 xx x = 175 + 125`

`( 7 + 5 ) xx x = 300`

`12 xx x = 300`

`x = 300 : 12`

`x = 25`

a) 7 x X +5 x X = 175 + 125.

7 + 5 x X = 300.

12 x X = 300.

x=300 : 12.

x=25.

Vậy X = 25.

Tick nha cảm ơn bạn.

giúp mình với

\(\frac{3+5+7+...+2015}{2+4+6+...+2014}+x=1\)

\(\frac{\left(3+2015\right).\left[\left(2015-3\right):2+1\right]:2}{\left(2+2014\right).\left[\left(2014-2\right):2+1\right]:2}+x=1\)

\(\frac{1016063}{1015056}+x=1\)

\(x=1-\frac{1016063}{1015056}\)

\(x=-\frac{1}{1008}\)