radical equation questions?

Question

find the products. simplify if possible
1.
(√(5) + 4) (√(5) - 2)

2.
(5√(2) -1)^2

Answer 1

1. 5-2sqrt5+4sqrt5-8
=-3+2sqrt 5
2.(5sqrt2)^2+(1)2-2*5 sqrt2
=25*2+1-10sqrt2
=51-10sqrt2

Answer 2

Hello

Use foil multiply first ones sqrt5*sqrt5 = 5
insides ones 4*sqrt5
out sides ones sqrt5*(-2)

Last ones 4*-2 giving us 5 +2sqrt5 -8 or

-3 + 2sqrt5


2. (5sqrt2 -1)(5sqrt2-1) = 50 -10sqrt2 +1 =
51 -10sqrt2
Hope This Helps!!