Question

if × = 5-√21,then the value of ×^2+1÷×^2

Answer 1

#Take the value of x. Find its reciprocal.
#Square them and add.
If it becomes complex then
#Take the sum of them and square it.
#Subtract 2 from it.
[since (x+1/x)^2 -2=x^2+1/x^2]

Answer 2

x=5-√21/2
=5-4.5826/2
=0.4174/2
=0.20871


now x²+¹/x²
=(0.20871)²+¹/(0.20871)²
=0.0435+¹/0.0435
=1.8949+1/0.0435
=2.8949/0.0435
=66.5494