( 2-√3)(2+√3)=2²-(√3)²=4-3=1

(5+√7)(5-√7)=5²-(√7)²=25-7=18

(6-2√5)(6+2√5)=6²-(2√5)²=36-20=16

(11-3√4)(3√4+11)=11²-(3√4)²121-36=85

(2√3+3√2)(3√2-2√3)=(3√2)²-(2√3)²=36-12=24

(2√7+5√2)(5√2-2√7)=(5√2)²-(2√7)²=50-28=22

( 2-√3)(2+√3) =4-3=1
(5+√7)(5-√7)=25-7=18
(6-2√5)(6+2√5)=36-4*5=36-20=16
(11-3√4)(3√4+11)=121-9*4=121-36=85
(2√3+3√2)(3√2-2√3)=9*2-4*3=18-12=6
(2√7+5√2)(5√2-2√7)=25*2-4*7=50-28=22
(3+√6)²=9+6√6+6=15+√6  
(5-√3)²=25-10√3+3=28-10√3
(2√7-5)²=28-20√7+25=53- 20√7 
(2√10+1)²=40+4√10+1=41+ 4√10 
(√7+2√2)²=7+4√14+8=15+ 4√14
(√6-3√2)²=6-6√12+18=24- 6√12 
(2√3-5√2)²=12-20√6+50=62-20√6 
(6√2+2√3)²=72+24√6+12=84+24√6 
(√7+√2-1)²= 

(√3+√5+1)²=

(√m-2)(√m+2)=m-4
(3-√k)(3+√k)=9-k
(√x+3√y)(3√y-√x)=9y-x
(2√k+√3t)(2√k-3√t)=4k-9t
(a√a+1)(a√a-1)=a^3-1
(√k+2ab)²=k+4ab√k+4a^2b^2
(√m-3c)²=m-6c√m+9c^2
(√a-√b)²=a-2√a√b+b  
(√p+√u)²=p+2√p√u+u