( \(-\dfrac{1}{2}\))² - \(\dfrac{5}{8}\) : (0,5)³ - \(\dfrac{5}{3}\) .(-6)

=  \(\dfrac{1}{4}\)   -  \(\dfrac{5}{8}\) : (\(\dfrac{1}{2}\))³ - \(\dfrac{5}{3}\) .( -6)

=   \(\dfrac{1}{4}\)  -  \(\dfrac{5}{8}\) : \(\dfrac{1}{8}\)  + 10

=    \(\dfrac{1}{4}\) -  5 + 10

= \(\dfrac{1}{4}+5\)

= 21/4

    \(\dfrac{8}{9}-\dfrac{1}{72}-\dfrac{1}{56}-\dfrac{1}{42}-.....-\dfrac{1}{6}-\dfrac{1}{2}\)

= \(\dfrac{8}{9}-(\dfrac{1}{72}+\dfrac{1}{56}+\dfrac{1}{42}+.....+\dfrac{1}{6}+\dfrac{1}{2})\)

=  \(\dfrac{8}{9}\) - \((\)\(\dfrac{1}{9.8}+\dfrac{1}{8.7}+\dfrac{1}{7.6}+\dfrac{1}{6.5}+.....+\dfrac{1}{1.2}\) \()\)

= \(\dfrac{8}{9}\)  - \((\) \(\dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+\dfrac{1}{4.5}+.....+\dfrac{1}{8.9}\)\()\)

= \(\dfrac{8}{9}\) - (\(\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+.....+\dfrac{1}{8}-\dfrac{1}{9}\)\()\)

= \(\dfrac{8}{9}\) - \((\) 1- \(\dfrac{1}{9}\))

= \(\dfrac{8}{9}\) - \(\dfrac{8}{9}\)

= 0

A=\(\dfrac{X-2}{X+1}\)=\(\dfrac{X+1-3}{X+1}\)=\(\dfrac{X+1}{X+1}-\dfrac{3}{X+1}\)ϵz
Nên 3⋮x+1 hay x+1 là ước của 3
mà Ư3={1,-1,3,-3}
ta có như sau : 
x+1=1          x+1=-1        x+1=3         x+1=-3
x=0              x=-2            x=2             x=-4
vậy x={0,-2,2,-4}

Trl dum tui vs

\(9^x.9^2+9^x=82\)

\(9^x.\left(9^2+1\right)\)= 82

\(9^x.82=82\)

\(9^x\)=1

=) x=0

ta có: V=a*b*c và S đáy:a*b

=>4,2=a*b*c=>4,2=a*b*1,2

=>4,2:1,2=a*b=>a*b=3,5

Vậy diện tích đáy bể là 3,5m^2