Докажите тождество -(12y – 3(y – 4)) + 9y = - 12

Question

Докажите тождество -(12y – 3(y – 4)) + 9y = - 12

Answer 1

-(12y-3(y-4))+9y=-12
-(12у-3у+12)+9у=-12
-(9у+12)+9у=-12
-9у-12+9у=-12
0=0
( y ∈ R )

Answer 2

-(12у-3(у-4))+9у=-(12у-3у+12)+9у=-12у+3у-12+9у=-12у
-12у=-12у
Тождество доказано