Question

若集合M = {x ∈R | 2 ^x ≥ 4}，N = {x∈R | x ² - 4 x + 3 ≥ 0}，則M∩N =

1. A.
   {x | x≤ 4}
2. B.
   {x | x≤ 1}
3. C.
   {x | x≥ 2}
4. D.
   {x | x≥ 3}

Answer 1

D
試題分析：根據(jù)題意，由于指數(shù)函數(shù)的單調(diào)性可知集合M = {x ∈R | 2 ^x ≥ 4}=｛x|x≥2｝，而根據(jù)一元二次不等式的求解可知N = {x∈R | x ² － 4 x + 3 ≥ 0}=,那么可知M∩N=，故選D.
考點：集合的交集
點評：解決的關(guān)鍵是對于指數(shù)函數(shù)的單調(diào)性和一元二次不等式的求解，屬于基礎(chǔ)題。