Question

ma puteti ajuta cu ex 5 si punctul b de la ex 4??

Answer 1

[tex]5.A=\{x\in Z|\frac{6}{x+2}\in Z\}\\ \frac{6}{x+2}\in Z\Rightarrow x+2\in D_6\\ x+2\in \{-6,-3,-2,-1;1,2,3,6\}\\ x\in \{-8,-5,-4,-3,-1,0,1,4\}\\ A=\{-8,-5,-4,-3,-1,0,1,4\}\\ B=\{x\in Z| \frac{9}{2x-1} \in Z\}\\ \frac{9}{2x-1}\in Z\Rightarrow 2x-1\in D_9\\ 2x-1 \in \{-9,-3,-1,1,3,9\}\\ 2x\in \{-8,-2,0,2,4,10\}\\ x\in \{-4,-1,0,1,2,5\}\\ B=\{-4,-1,0,1,2,5\}\\ ....................................\\ 4.b)|(-1)^1+(-1)^2+...+(-1)^{1499}|=\\ |-1+1-1+1-1+...+1-1|=\\ |-1|=\boxed{1}[/tex]