(a-2)x6+2x(7-5)x6-30=0​

Răspuns :

(a-2)•6+2•2•6-30=0
(a-2)•6+24-30=0
(a-2)•6+24=30
(a-2)•6=30-24=6
a-2=6:6=1
a=1+2
a=3