√5(√3+√7)=√15+√35
(√10-√3)(√10+√3)=(√10)²-(√3)²=10-3=7
(√7+√5)²=(√7)²+√70+(√5)²=12+√70
√35-√15/√14-√6 =√5(√7-√3)/√2(√7-√3)=
√5/√2=√2,5
√а-√b/a-b=√а-√b/ (√a-√b)(√a+√b)=
= 1/ √a+√b=
x-2√xy+y/x-y= (√x-√y)²/(√x-√y)(√x+√y)=
(√x-√y)/ (√x+√y)
a-9/√a+3= (√a+3)(√a-3)/(√a+3)=√a-3