13+13=26

mk nhanh nhất t cho mk đi

=26 mình nhanh nất

a) 15 x 12 - 3 x 5 x 10

   = 15 x 12 - 15 x 10

   = 15 x (12 - 10)

   = 15 x 2

   = 30

C2 : 15 x 12 - 3 x 5 x 10

= 180 - 150

= 30

b) 45 - 9 x (13 + 5)

= 45 - 9 x 18

= 9 x 5  - 9 x 18

= 9 x (5 - 18)

= 9 x (-13)

= -117

c) 29 x (19 - 13) - 19 x (29 - 13)

= 29 x 6 - 19 x 16

= 174 - 304

= -130

39/35

\(\frac{3}{5}\).\(\frac{-9}{13}\)+\(\frac{4}{13}\).\(\frac{-3}{5}\)+\(\frac{12}{7}\)=\(\frac{3}{5}\).\(\frac{-9}{13}\)+\(\frac{-4}{13}\).\(\frac{3}{5}\)+\(\frac{12}{7}\)

                                                                =\(\frac{3}{5}\).(\(\frac{-9}{13}\)+\(\frac{-4}{13}\))+\(\frac{12}{7}\)

                                                                =     \(\frac{3}{5}\).-1+\(\frac{12}{7}\)

                                                                =\(\frac{-3}{5}\)+\(\frac{12}{7}\)

                                                              =\(\frac{39}{35}\)

Làm ơn đó

Ai làm dc mik tặng 500 robux

    \(\dfrac{7}{19}\).\(\dfrac{5}{19}\) + \(\dfrac{7}{19}\).\(\dfrac{8}{13}\) + \(\dfrac{12}{19}\)

=   \(\dfrac{7}{19}\).( \(\dfrac{5}{13}+\dfrac{8}{13}\)) + \(\dfrac{12}{19}\)

= \(\dfrac{7}{19}\) . \(\dfrac{13}{13}\) + \(\dfrac{12}{19}\)

= \(\dfrac{7}{19}\) + \(\dfrac{12}{19}\)

= \(\dfrac{19}{19}\)

= 1 

   $\genfrac{}{}{0ex}{}{7}{19}$.$\genfrac{}{}{0ex}{}{5}{19}$ + $\genfrac{}{}{0ex}{}{7}{19}$.$\genfrac{}{}{0ex}{}{8}{13}$ + $\genfrac{}{}{0ex}{}{12}{19}$

=   $\genfrac{}{}{0ex}{}{7}{19}$.( $\genfrac{}{}{0ex}{}{5}{13}+\genfrac{}{}{0ex}{}{8}{13}$) + $\genfrac{}{}{0ex}{}{12}{19}$

= $\genfrac{}{}{0ex}{}{7}{19}$ . $\genfrac{}{}{0ex}{}{13}{13}$ + $\genfrac{}{}{0ex}{}{12}{19}$

= $\genfrac{}{}{0ex}{}{7}{19}$ + $\genfrac{}{}{0ex}{}{12}{19}$

= $\genfrac{}{}{0ex}{}{19}{19}$

= 1 

tổng của hai số lẻ liên tiếp là 636 . Tìm số bé hơn

Bài 1:

\(\frac{3}{7}\cdot\frac{9}{2}-\frac{1}{14}\cdot\frac{1}{13}\)=\(\frac{27}{14}-\frac{1}{14}\cdot\frac{1}{13}\)

                                          = \(\frac{1}{14}\left(27-\frac{1}{3}\right)\)

                                         = \(\frac{1}{14}\cdot\frac{350}{13}\)=\(\frac{25}{13}\)

bài 2:\(\frac{5}{9}\cdot\frac{7}{13}+\frac{5}{9}\cdot\frac{9}{13}\cdot\frac{3}{13}\)= \(\frac{5}{9}\cdot\frac{1}{13}\left(7+9\cdot\frac{3}{13}\right)\)

                                                            = \(\frac{5}{9}\cdot\frac{1}{13}\cdot\frac{94}{13}\)=\(\frac{470}{1521}\)

có j sai xin mn chỉ bảo!

\(|2x-5|=13\)

TH1: \(2x-5=13\)

\(2x=18\)

\(x=9\)

TH2: \(2x-5=-13\)

\(2x=-8\)

\(x=-4\)

Vậy: \(x\in\left\{-4;9\right\}\)

=.= hk tốt!!

\(\left|2x-5\right|=13\)

\(\Leftrightarrow\orbr{\begin{cases}2x-5=13\\2x-5=-13\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=9\\x=-4\end{cases}}\)

\(\left|5x-2\right|\le13\)

\(\Rightarrow x\in\left\{-1;0;1;2;3\right\}\)