1/5.6+1/6.7+1/7.8+... +1/x.(x+1)=1/5-x+1/225
Câu 1: Tính
a, A = 1/2 + 1/6 + 1/12 + 1/20 + 1/30 + 1/42 + + 1/56 + 1/72
b, B = 1/5.6 + 1/6.7 + 1/7.8 + .... + 1/24.25
1, 1/7 + 1/91 + 1/247 + 1/475 + 1/775 + 1/1147
2, 1/6 + 5/6.7 + 1/7.8 + 5/8.9 + ... + 1/24.25
3, 22/5.7 + 22/7.9 + 22/9.11 + ... + 22/39.41
Tìm x:
a, (x - 1/2) : 1/3 + 5/7 = 9 5/7
b, x + 30% x = - 1,31
c, -2/3.x + 1/5 = 1/10
5/3-x+1/5=-3/10
x-(1-1/4)=2/3
1-5/3=1/5-x
bài 1: tìm x
a) 8/23 . 46/24 = 1/3 . x
b) 1/5 : x = 1/5 - 1/7
c) 4/9 - (x - 1/2) mũ 2 = 1/3
d)3,2 . x - (4/5 + 2/3) : 3 2/3 = 7/10
bài 20 : tìm x
\(\dfrac{1}{1.2}\)+\(\dfrac{1}{2.3}\)+...+ \(\dfrac{1}{x.\left(x+1\right)}\)+\(\dfrac{1}{2018.2019}\)
bài 21: tìm x
\(\dfrac{x+1}{99}\)+\(\dfrac{x+2}{98}\)+\(\dfrac{x+3}{97}\)+\(\dfrac{x+4}{96}\)=-4
bài 22: so sánh
a) \(\dfrac{-1}{5}\)+\(\dfrac{4}{-5}\) và 1
b) \(\dfrac{3}{5}\) và \(\dfrac{2}{3}\)+\(\dfrac{-1}{5}\)
c) \(\dfrac{3}{2}\)+\(\dfrac{-4}{3}\) và \(\dfrac{1}{10}\)+\(\dfrac{-4}{5}\)
d)\(\dfrac{1}{2}\)+\(\dfrac{1}{3}\)+\(\dfrac{1}{4}\)+\(\dfrac{1}{5}\)+\(\dfrac{1}{6}\) và 2
1/3.4+1/4.5+1/5.6+...+1/20/21
Tìm x:
a)1/x +1/2=-1/2 -3/2
b)-1/x -1/2=-5
c)x/2 - 1/5=6
d)1/2-(x/2-1/2)=-7
e)2-(2-x)=7/4
f)1/x-1=7/4
g)1/1-x=7/4
Các bạn giúp mik với, mai mình phải học online r mà đây là btvn.Trong tối nay nha.Cảm ơn rất nhiều