( 1)

(4√ 12 -6√7)÷√3=(8√3)/√3-(6√7)/√3=8-2√2 1

(2)

[√ 18-4√( 1/2)]×√( 1/2)=(3√2-2√2)×√( 1/2)=√2×(√2)/2= 1

23

(4√3+3√2)? =(4√3)? +2*(4√3)*(3√2)+(3√2)? =48+24√6+ 18=66+24√6

24

(√a+√b)？ -(√a-√b)？ =(√a)？ +2√a *√b+(√b)？ -[(√a)？ -2√a *√b+(√b)？ ]

=a+2√(ab)+b-a+2√(ab)-b=4√(ab)

25

∵C is the symmetry point of b about a.

The coordinate of ∴C is x=2-√2.

X? -4x+4=(x-2)？ =(2-√2-2)? =(-√2)? =2

26

( 10√ 15+5√5)? -( 10√ 15-5√5)?

=( 10√ 15)? +2* 10√ 15 *5√5+(5√5)? -( 10√ 15)? +2* 10√ 15 *5√5-(5√5)?

=4* 10√ 15 *5√5

=200√75