Class 9th math Review Exercise 3 solution english PCTB

Question 9: From suitable properties of union and intersection, deduce the following results:

\((ii)\) \(\;\) \(A\cup (A\cap B)=A\cap (A\cup B)\)

Solution:

\(\text{L.H.S.}=A\cup (A\cap B)\)

\(\ \ \ \ \ \ \ \ \ \ \ =[A\cup A]\cap[A\cup B)\) \(\quad\)\(\because\ \) distribution of union over intersection

\(\ \ \ \ \ \ \ \ \ \ \ =A\cap (A\cup B)\)

Hence, \(\text{L.H.S.}=\text{R.H.S.}\)

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