Question Number 9423 by Rohit kumar last updated on 08/Dec/16
$${if}\:{x}\:{and}\:{y}\:{are}\:{two}\:{sets}\:{such}\:{that}\:{n}\left({x}\right) \\ $$$$=\mathrm{17}\:,\:{n}\left({y}\right)=\mathrm{23}\:{and}\:{n}\left({X}\cup{Y}\right)\:=\mathrm{38}, \\ $$$$\boldsymbol{{find}}\:\boldsymbol{{n}}\left({X}\cup{Y}\right). \\ $$
Commented by sandy_suhendra last updated on 08/Dec/16
$$\mathrm{do}\:\mathrm{you}\:\mathrm{mean}\:\mathrm{n}\left(\mathrm{X}\cap\mathrm{Y}\right)\:? \\ $$
Commented by Rohit kumar last updated on 08/Dec/16
$${x}\cup{y} \\ $$$$ \\ $$
Commented by RasheedSoomro last updated on 08/Dec/16
$$\mathrm{n}\left({x}\cup{y}\right)=\mathrm{38}\:\left(\mathrm{Given}\right) \\ $$
Answered by sandy_suhendra last updated on 08/Dec/16
$$\mathrm{n}\left(\mathrm{X}\cup\mathrm{Y}\right)=\mathrm{n}\left(\mathrm{X}\right)+\mathrm{n}\left(\mathrm{Y}\right)−\mathrm{n}\left(\mathrm{X}\cap\mathrm{Y}\right) \\ $$$$\mathrm{where}\:\cup=\mathrm{unions}\:\mathrm{and}\:\cap=\mathrm{intersections} \\ $$