Tính A = 1 / 2.4 + 1 / 4.6 + … + 1 / 48.50 21/08/2021 Bởi Elliana Tính A = 1 / 2.4 + 1 / 4.6 + … + 1 / 48.50
TRẢ LỜI : `A=` $\frac{1}{2.4}$ `+` $\frac{1}{4.6}$ `+…` $\frac{1}{48.50}$ `A=` $\frac{1}{2}$ . ($\frac{2}{2.4}$ `+` $\frac{2}{4.6}$ `+…`$\frac{2}{48.50}$ ) `A=` $\frac{1}{2}$ `.`($\frac{1}{2}$`-`$\frac{1}{4}$ `+` $\frac{1}{4}$ `-` $\frac{1}{6}$ `+…+` $\frac{1}{48}$`-`$\frac{1}{50}$ ) `A=`$\frac{1}{2}$ `.`($\frac{1}{2}$`-`$\frac{1}{50}$ ) `A=` $\frac{1}{2}$ `.` $\frac{12}{25}$ `A=` $\frac{6}{25}$ _________ Học tốt ^^ Xin hay nhất >< Bình luận
Giải thích: A=1/2.4+1/4.6+…+1/48.50 ⇔ 2A=2/2.4+2/4.6+…+2/48.50 2A=1/2-1/4+1/4-1/6+…+1/48-1/50 2A=1/2-1/50=25/50-1/50 2A=24/50 A=24/50÷2 A=24/100 Bình luận
TRẢ LỜI :
`A=` $\frac{1}{2.4}$ `+` $\frac{1}{4.6}$ `+…` $\frac{1}{48.50}$
`A=` $\frac{1}{2}$ . ($\frac{2}{2.4}$ `+` $\frac{2}{4.6}$ `+…`$\frac{2}{48.50}$ )
`A=` $\frac{1}{2}$ `.`($\frac{1}{2}$`-`$\frac{1}{4}$ `+` $\frac{1}{4}$ `-` $\frac{1}{6}$ `+…+` $\frac{1}{48}$`-`$\frac{1}{50}$ )
`A=`$\frac{1}{2}$ `.`($\frac{1}{2}$`-`$\frac{1}{50}$ )
`A=` $\frac{1}{2}$ `.` $\frac{12}{25}$
`A=` $\frac{6}{25}$
_________
Học tốt ^^
Xin hay nhất ><
Giải thích:
A=1/2.4+1/4.6+…+1/48.50
⇔ 2A=2/2.4+2/4.6+…+2/48.50
2A=1/2-1/4+1/4-1/6+…+1/48-1/50
2A=1/2-1/50=25/50-1/50
2A=24/50
A=24/50÷2
A=24/100