Question

||y+2|-y|, если y<-2

Answer 1

$y<-2\; \; \Rightarrow \; \; (y+2)<0\; \; \to \; \; |y+2|=-(y+2)=-y-2\; ,\\\\\\||y+2|-y|=|-y-2-y|=|-2y-2|=|-2(y+1)|=\\\\=|-2|\cdot |y+1|=2\cdot |y+1|=\\\\=\Big [\; y<-2\; \; \Rightarrow \; \; (y+1)<-1<0\; \; \Rightarrow \; \; |y+1|=-(y+1)=-y-1\; \Big ]=\\\\=2\cdot (-y-1)=-2\cdot (y+1)$