6
5
4
3
Correct answer is D
(√x+1)∗(√x−1)=4⟹√x+1√x−1+√x−1√x+1=4
(√x+1)(√x+1)+(√x−1)(√x−1)(√x−1)(√x+1)
= x+2√x+1+x−2√x+1x−1⟹2x+2x−1=4
2x+2=4x−4∴
x = 3
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