If x=√5−2√5+2 then x2 =
161−72√5
x=√5−2√5+2
=√5−2√5+2×√5−2√5−2
=(√5−2)2(√5)2−(2)2 (The numerator is of the form (a−b)2 and the denominator is of the form a2−b2)
=(√5)2−2(2√5)+(2)25−4
=5−4√5+41
=9−4√2
X2=(9−4√5)2
=(9)2−2(9)(4√5)+(4√5)2
=81−72√5+80
=161−72√5