=>( y - 1/2 )+( y - 1/6 )+...+( y- 1/90 ) = 1
=>y + y+.. + y - 1/2 - 1/6-...- 1/90 = 1
=>y + y+..+ y - 1/(1x2) - 1/(2x3) - 1/(3x4)-...- 1/(9x10) = 1
=> 9y -( 2-1)/(1x2) - (3-2)/(2x3)-...- (10-9)/(9x10) = 1
=>9y- 2/(1x2) + 1(1x2) - 3/(2x3) + 2/(2x3)-...- 10/(9x10) + 9(9x10) = 1
=> 9y- 1 + 1/2 - 1/2 + 1/3-...- 1/9 + 1/10 = 1
=>9y- 1 + 1/10 = 1
=> 9y- 9/10 =1
=>y=19/90
Vậy y=19/90
Y x \(\dfrac{1}{2}\) + Y x \(\dfrac{1}{6}\) + Y x \(\dfrac{1}{12}\) + Y x \(\dfrac{1}{20}\) = \(\dfrac{8}{5}\)
Y+2/5=17/12-5/6 là: y. Y-1/3=7/15+2/5
1716 : y = 12 x 13 y x 2/3 + y x 1/6 = 10/3
bài 1: Tính
a} 5/12 + 1/3 x 3/5 =
B 7/5 - 4/9 : 2/5 =
C 2/5 x 1/4 : 2/5 =
bài 2: Tìm y
a 42/25 : y/5 = 5/6
b 27/y : 9/4 = 3/7
.6 km2 10 m2 = … m2
11.Tính: 5 x 4/5 = ...
12.Tìm y biết: y + 1/2 = 4/5
Vậy y = ...
Tìm y biết :12-y/y-1=3/2 : 1/2
4/x=12/15=y/45 3/x=1/y=6 / 24
Tìm y biết:(y+1)+(Y+2)+(Y+3)=12
Nếu (y + 1) + (Y + 2) + (Y + 3) = 12 thì Y = ..........
