9.2
10.56
1 1.2 root 3 divided by 3 (2 is wrong, please note A >；; b)
12
The square root of 13 6 divided by 3 *a a a.
14.( 1, root number 3)
15. Root number 3
16.( 1) Omit (2) 1/2.
17.( 1) 177 (2)0.5
18.( 1) Root sign 15 divided by 5.
19.( 1) is greater than or equal to 3 (2), which is discussed in different situations, that is, x = 1, and x = root sign [(8a+ 1)- 1]/4.
20. (1) x 2/4+y 2 =1(2) Prove that the problem (3) exists, the area is forgotten, and m is (0,-1).
21.(1) 2n (2) 2 (2n+1)-4 (3) proof problem
Note: 2 n refers to the n power of 2, and some answers may be remembered incorrectly. Please point out.