1)(√2-1)⁵⁰•(√2+1)⁵⁰ = [(√2-1)(√2+1)]⁵⁰ = (2-1)⁵⁰=1⁵⁰=1
c)(√2+√3-1)²-(√2+ √3)²+2(√2+√3)=
=(√2+√3-1)(√2+√3-1)-(√2+ √3)²+2(√2+√3)=
=2+√6-√2+√6+2-√3-√2-√3+1-5-2√6+2√2+2√3=
=2+2+1-5=0
2)daca x+y=4 si √xy=2 atunci
a)
(√x+√y )²=x+y+2√xy =4+4=8
√x+√y =√8 =2√2
√x+√y =2√2
b)
(√x-√y )²=x+y-2√xy =4-4=0
√x-√y =0
c)x²+y² = (x+y)² -2xy =16-2*4=8
√xy=2
xy=4
x²+y²=8