Solve the inequation 3 ≥ (x−2)2 + x3, x ∈ N. Find the cardinality(number of elements) of the set representing all the possible values of x.
4
3 ≥ (x−2)2+x3
or 3 ≥ [3(x−2)+2x]6
or 3 ≥ (3x−6+2x)6
or 3 ≥ (5x−6)6
Multiplying both sides by 6, we get:
6 × 3 ≥ 6[(5x−6)6]
or 18 ≥ 5x-6
or 18+6 ≥ 5x
or 24 ≥ 5x
or x ≤ 4.8
Since x ∈ N, x = {1, 2, 3, 4}.
So, the cardinality of the set is 4.