Question

in both of these answers (a-b)^2 formula is applied which one is correct and why or which one is wrong but why​

Answer 1

Answer:

$\sqrt{7-4\sqrt{3}}\\\\=\sqrt{(2-\sqrt{3})^2}\\\\=|{2-\sqrt{3}}|\\\\=2-\sqrt{3} \;\;\;or\;\;\;-2+\sqrt{3}$

BOTH THE ANSWERS ARE CORRECT.

BUT FOR THIS TYPE OF QUESTIONS

YOU MUST ALWAYS CHOOSE THE POSITIVE ANSWER IF NO EXTRA CONDITION   REGARDING THE ANSWER IS GIVEN.

AND FURTHER THIS QUESTION CAN BE GENERATED IN TWO WAYS AS (-1)

TO THE POWER AN EVEN NUMBER IS ALWAYS ONE

AND IS SAME TO THAT ANSWER THAT ACCOMPANIES ONE INSTEAD OF ITS NEGATION.

HOPE IT HELPS....