Question

6.If x=√5+2, then x-1/x equals to
1 point
A. 2√5
B. 4
C. 2
D. √5
Other:​

Answer 1

Answer:

x=5^1/2+2

x-1/x=5^1/2+2-1÷5^1/2+2

=(5^1/2+2)(5^1/2+2)-1÷5^1/2+2

=5+4+4(5)^1/2-1÷5^1/2+2

=8+4(5)^1/2÷5^1/2+2

=4(2+(5)^1/2)÷5^1/2+2

=4(1)÷(1)

=4

option B.4 is the answer