3 votes 3 votes In a Group (G,*) the equation $x * a = b $ has a a) unique solution $b * a^{-1}$ b) unique solution $a^{-1} * b$ c) unique solution $a^{-1} * b^{-1}$ d) many solutions Set Theory & Algebra set-theory&algebra + – Mojo-Jojo asked Jan 1, 2016 Mojo-Jojo 384 views answer comment Share Follow See all 0 reply Please log in or register to add a comment.
Best answer 3 votes 3 votes In a group 1] there exist a unique identity element of Group i.e G. lets call it ' e ' 2] the inverse of any element in G is unique. We generally represent inverse of a element 'a' as $a^{-1}$ Now the equation is x*a = b post multiply by $a^{-1}$ both side, x*a*$a^{-1}$ = b * $a^{-1}$ x* e = b * $a^{-1}$ x = b * $a^{-1}$ $\because $ there always exit only unique inverse of any element in Group so solution to this equation is also unique. Ref : https://en.wikipedia.org/wiki/Group_(mathematics)#Uniqueness_of_identity_element_and_inverses This way answer is a) Unique Solution b * $a^{-1}$ Sandeep Singh answered Jan 1, 2016 • selected Jan 1, 2016 by Mojo-Jojo Sandeep Singh comment Share Follow See 1 comment See all 1 1 comment reply Mojo-Jojo commented Jan 1, 2016 reply Follow Share The answer given is option c, Don't know how :'( 0 votes 0 votes Please log in or register to add a comment.