12. 原式

11. 解：原式····························································································· 3分

6分

10. 解：原式

9. 解：原式································ (4分)

8. 解：原式＝

　　　　　　　　 ＝＝2

7. 2+2

6. 解：＝

5. 解：原式=2+1-3+2　　　　　　　　　　　　　　　　　　　　　 　……4分

　　　　　　　 =2　　　　　　　　　　　　　　　　　　　　　　　　　 ……2分

4. 解：原式························································································ 2分

·········································································································· 5分

···················································································································· 6分

3. 解：原式········································································ 4分

································································································ 5分

······················································································································ 6分