প্রশ্ন: A = {x : x ∈ R এবং x² - (a + b) x + ab = 0} এবং B = {a, b, c} হলে (A ∪ B) = কত?

সমাধান:
A = {x : x ∈ R এবং x² - (a + b) x + ab = 0}
এবং B = {a, b, c}

এখানে
x² - (a + b)x + ab = 0
x² - ax - bx + ab = 0
x(x - a) - b(x - a) = 0
(x - a)(x - b) = 0
x = a, b

A ={a, b}
B = {a, b, c}

A ∪ B = {a, b} ∪ {a, b, c} = {a, b, c}