Question

根據(jù)下列兩組x、y的值，求出代數(shù)式的值．
（1）；                     
（2）滿足的x、y的值．

Answer 1

（1）當(dāng)時(shí)，························································· （1分）
，···················································· （3分）
.··········································································· （4分）
（2）由非負(fù)性可知·························································· （6分）
當(dāng)時(shí)，
，······················································ （7分）
.      （8分）

試題分析：（1）把x、y的值代入代數(shù)式，運(yùn)用有理數(shù)的混合運(yùn)算求值．
（2）利用絕對值和完全平方都大于或等于0得出x、y的值.
點(diǎn)評：熟練運(yùn)用合并同類項(xiàng)的法則，利用絕對值和完全平方不小零從而列出方程求解．