is

\(|x|=6\) 

\(\Rightarrow x=6\) hoặc -6

vậy...

29.34-34.59

=34.(29-59)

=34.-30

=-1020

29.34-34.59

=34.(29-59)

=34.(-30)

=-1020

have

CMR : \(\dfrac{2}{5}< A< \dfrac{8}{9}\)

Với \(A=\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+\dfrac{1}{5^2}+\dfrac{1}{6^2}+\dfrac{1}{7^2}+\dfrac{1}{8^2}+\dfrac{1}{9^2}\)

B12

a) ta có \(\dfrac{170}{17}=10\Rightarrow x=9\)

b) ta có  \(\dfrac{13}{3}=4,333...\Rightarrow x=4\)

B13

a) x>\(\dfrac{-12}{13}\Rightarrow x=-1\)

b) ta có: \(\dfrac{-45}{15}\Rightarrow x>-3\Rightarrow x=-2\)

-2.-2.-2=4.-2=-8