A=1/21+1/28+1/36+...+2/x(x+1)=2/9
tìm x biết 1/21+1/28+1/36+.................+1/x.(x+1)=2/9
Tìm x biết:
1/21+1/28+1/36+...+1/x(x+1):2 = 2/9
Các bạn giải giúp mình với!
Tìm x
\(\frac{1}{21}\)+\(\frac{1}{28}\)+\(\frac{1}{36}\)+..........+\(\frac{2}{x\left(x+1\right)}\)=\(\frac{2}{9}\)
a,tim x biet |x-2|+|3-2x|=2x+1
b,tim x,y thuoc Z biet xy+2x-y=5
c, tinh A=(1-1/15)(1-1/21)(1-1/28).....(1-1/210)
\(\frac{1}{15}+\frac{1}{21}+\frac{1}{28}+\frac{1}{36}+...+\frac{2}{x\left(x+1\right)}=\frac{11}{40}\)
Tìm x biết:
\(\dfrac{1}{15}+\dfrac{1}{21}+\dfrac{1}{28}+\dfrac{1}{36}+...+\dfrac{2}{x\left(x+1\right)}=\dfrac{11}{40},\left(x\inℕ^∗\right)\)
Giải chi tiết giúp mik nha.
1 tim cac so nguyen x,y biet x/7=6/21 -5/y=20/28 1/2=x/12 x/8=-28/32 3/y=12/24 3/4=15/y 2 viet 3 phan so bang phan so -10/15
S=(1-1/21)x(1-1/28)x(1-1/36)x....(1-1/1326)