a,3x - 5 = -7 - 13
3x = -7-13+5
3x = -15
x =-15 : 3
x = -5
b,2x - (-3) = 7
2x + 3 = 7
2x = 7 - 3
2x = 4
x = 4:2
x = 2
c,( x - 5 ).( x + 6 ) = 0
\(\left[ \begin{array}{l}x-5=0\\x+6=0\end{array} \right.\)
\(\left[ \begin{array}{l}x=0+5\\x=0-6\end{array} \right.\)
\(\left[ \begin{array}{l}x=5\\x=-6\end{array} \right.\)
d,| x | - 10 = -3
| x |= -3 + 10
| x | = 7
Hoặc x = -7