Question

write the cardinal number of the set B = {x:x € Q and x²-5}​

Answer 1

Answer:

n(B) = ∅

Step-by-step explanation:

Since x is not equal x² - 5, the number of elements, the cardinality of B = {x:x € Q and x²-5} = 0

If x² - 5 = 0, then also B = ∅

Since the possible values are √5 and -√5 which are not rational numbers