Question

已知a=，求的值．

Answer 1

【答案】分析：先化簡，再代入求值即可．
解答：解：∵a=，
∴a=2-＜1，
∴原式=-
=a-1-
=a-1+
=2--1+2+
=4-1
=3．
點評：本題考查了二次根式的化簡與求值，將二次根式的化簡是解此題的關鍵．