Question

若代數(shù)式是五次二項(xiàng)式，則a的值為

1. A.
   2
2. B.
   ±2
3. C.
   3
4. D.
   ±3

Answer 1

A
分析：先觀察多項(xiàng)式的各項(xiàng)，再確定每項(xiàng)的次數(shù)，最高次項(xiàng)的次數(shù)就是多項(xiàng)式的次數(shù)．
解答：由題意得：a²-1+2=5且a+2≠0，
解得a=2．
故選A．
點(diǎn)評(píng)：本題考查了多項(xiàng)式的定義，應(yīng)從次數(shù)和項(xiàng)數(shù)兩方面進(jìn)行考慮．解題的關(guān)鍵是弄清多項(xiàng)式次數(shù)是多項(xiàng)式中次數(shù)最高的項(xiàng)的次數(shù)．注意本題最高次項(xiàng)的系數(shù)不等于0．