Số cặp số của tổng trên là : 

\(\left(50-1\right):1+1=50\) ( cặp ) 

Ta có : 

( y +1 ) + ( y + 2 ) + ( y + 3 ) + .... + ( y + 50 ) = 1425 

<=> 50y + 1 + 2 + 3 + ... + 50 = 1425

<=> 50y + \(\dfrac{\left(50+1\right).50}{2}\) =1425

<=>50y + 1275 = 1425 

<=> 50y = 150

<=> y = 3 

A= 1/30 + 1/42 + 1/56 + 1/72 + 1/90 + 1/110 + 1/132

A=1/5x6+1/6x7+1/7x8+1/8x9+1/9x10+1/10x11+1/11x12

A=1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11+1/11-1/12

A=1/5-1/12

A=... chắc vậy:V

\(\left(\dfrac{1}{16}\right)^x=\left(\dfrac{1}{2}\right)^{10}\)

\(\Leftrightarrow\left[\left(\dfrac{1}{2}\right)^4\right]^x=\left(\dfrac{1}{2}\right)^{10}\)

\(\Leftrightarrow\left(\dfrac{1}{2}\right)^{4x}=\left(\dfrac{1}{2}\right)^{10}\)

\(\Leftrightarrow4x=10\)

\(\Leftrightarrow x=\dfrac{5}{2}\)

(1/16)x =(1/2)10

 = (1/4)⁵ = ( 1/2)^{1 0} 

\(=3\left(\dfrac{2}{3.5}+\dfrac{2}{5.7}+\dfrac{2}{7.9}+...+\dfrac{2}{99.101}\right)=\)

\(=3\left(\dfrac{5-3}{3.5}+\dfrac{7-5}{5.7}+\dfrac{9-7}{7.9}+...+\dfrac{101-99}{99.101}\right)=\)

\(=3\left(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+...+\dfrac{1}{99}-\dfrac{1}{101}\right)=\)

\(=3\left(\dfrac{1}{3}-\dfrac{1}{101}\right)=\dfrac{3.98}{101}\)