a= 1/1.2 +1/2.3+1/3.4+ ...+ 1/x.x+1

S = \(\dfrac{-1}{1.2}\) - \(\dfrac{1}{2.3}\) - \(\dfrac{1}{3.4}\) - - - \(\dfrac{1}{\left(n-1\right).n}\) ( tính)

help yourself with home !!!!!!!!!!!!

( 3-1/4 + 2/3 ) - ( 5 + 1/3 - 6/5 ) - ( 6- 7/4 - 3/2 )

A = ( 6 - \(\dfrac{2}{3}\) + \(\dfrac{1}{2}\)) - ( 5 + \(\dfrac{5}{3}\) - \(\dfrac{3}{2}\)) - (3 - \(\dfrac{7}{3}\) + \(\dfrac{5}{2}\))

tính nhanh :

a,\(\dfrac{4}{3}\) - [(\(\dfrac{-11}{6}\) )- (\(\dfrac{2}{9}\) + \(\dfrac{5}{3}\))]

b, (8- \(\dfrac{9}{4}\) +\(\dfrac{2}{7}\) ) - ( -6 -\(\dfrac{3}{7}\) +\(\dfrac{5}{4}\) ) - ( 3+ \(\dfrac{2}{4}\) - \(\dfrac{9}{7}\) )

x-3=5-x

Tìm x biết: (x-3)^2-x|x-3|=0

tim a b \(\in Q\)

a, a - b = 2 \(\left(a+b\right)=a\div b\)

b, a + b = a . b = a \(\div\) b

giup minh nhe minh dang can gap

mẫu chung của 9;6;4

tìm x biết :

\(\dfrac{-4}{7}-x=\dfrac{3}{5}-2\cdot x\)

giúp mk nha 5h đi học rùi