=> 1/24 - 1/25 + 1/25 - 1/ 26 + .... + 1/29 - 1/30 + x : 1/3 = -4
=> 1/24 - 1/30 + x : 1/3 = - 4
=> 1/ 120 + x : 1/3 = -4
=> x : 1/3 = 481/120
=> x = 481/360
Vậy x = 481/360
\(\frac{1}{24.25}+\frac{1}{25.26}+...+\frac{1}{29.30}+x:\frac{1}{3}=-4\)
\(\Rightarrow\frac{1}{24}-\frac{1}{25}+\frac{1}{25}-\frac{1}{26}+...+\frac{1}{29}-\frac{1}{30}+x\times3=-4\)
\(\Rightarrow\frac{1}{24}-\frac{1}{30}+3x=-4\)
\(\Rightarrow\frac{1}{120}+3x=-4\)
=(1/24-1/25+1/25-1/24+...+1/29-1/30)+x:1/3=-4
=(1/24-1/30)+x:1/3=-4
=1/120+x:1/3=-4
x:1/3=-4-1/120
x:1/3=-481/120
x=-481/120.1/3
x=-481/360
số to lắm bạn nhé!