92. 1)) тк знаменатель одинаковый, тогда:
=(2a -50) /(√a +5) =
=2(a -25)(√a -5) /(√a +5)(√a -5) =
=2(a -25)(√a -5) /(a -25) =2(√a -5)=2√a -10
2) y -√7 = -(√7 -y)
=(21 -3y²) /(√7 -y) =3(7 -y²)(√7 +y) /(√7 -y)(√7+y)=
=3(7 -y²)(√7 +y) /(7 -y²)=
=3(√7 +y) =3√7 +3y
3) 22√n /11(√a -√b) ×(a -b)/10√n =
=2√n×(a -b) /10√n×(√a -√b) =
=(a -b)(√a +√b) /5(√a -√b)(√a +√b) =
=(a -b)(√a +√b) /5(a -b) =
=(√a +√b)/5
4). =15√d ×(a -c) /30√d×(√ab +√bc) =
=(a -c) /2(√ab +√bc) =
=(a -c)(√ab -√bc) /2(√ab+√bc)(√ab -√bc) =
=(a -c)(√ab -√bc) /2(ab -bc) =
=(a -c)(√ab -√bc) /2b(a -c) =
(√ab -√bc) /2b