\(-12\left(x-5\right)+7\left(3-x\right)=15\)

\(\Rightarrow-12x+60+21-7x=15\)

\(\Rightarrow-12x-7x=15-21-60\)

\(\Rightarrow-19x=-66\)

\(\Rightarrow x=\frac{66}{19}\)

\(\left|2x-5\right|=12\)

\(\Leftrightarrow\orbr{\begin{cases}2x-5=12\\2x-5=-12\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}2x=17\\2x=-7\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=\frac{17}{2}\left(t/m\right)\\x=-\frac{7}{2}\left(t/m\right)\end{cases}}\)

-12( x - 5 ) + 7(3 - x ) = 15

=> -12x +60 + 21 - 7x = 15

=> -12x - 7x + 60 + 21 = 15

=> -19x + 81 = 15

=> -19x = 15 - 81 = -66

=> x = 66/19

-ab-ab

=-(ab+ab)

=-2ab

7x-19x+6x

=[7-19+6].x

=[(-12)+6].x

=-6x

A=7x-14x+6x

=(7x-6x)-14x

=1x-14x=-(13x)

B=-ab-ab-ab-ab=-(ab+ab+ab+ab)

=-(4ab)

thank nhé

A=7x-14x+6x

  =x.(7-14+6)

=x.(-1)

=-x

B=-ab-ab-ab-ab

  =-(ab+ab+ab+ab)

  =-(4ab)

  =-4ab

a) 7x-19x+6x=  -6x

b) -ab-ab=-ab+(-ab)=-2ab

a) Ta có: 7x - 19x + 6x

= x. ( 7 - 19 + 6 )

= x. ( - 6 )

b) Ta có: -ab - ba

= b. ( -a - a )

= b . [ ( -2 ) .a ]

a.x(7-19+6)