If x = √5 + 2, find x²-4√5.
2025
If x = √5 + 2, find x²-4√5.
- A.
1
- B.
7
- C.
9
- D.
3
Attempted by 20 students.
Show answer & explanation
Correct answer: C
x = sqrt(5) + 2, so x^2 = 5 + 4 + 4sqrt(5) = 9 + 4sqrt(5). Hence x^2 - 4sqrt(5) = 9.
2025
If x = √5 + 2, find x²-4√5.
1
7
9
3
Attempted by 20 students.
Correct answer: C
x = sqrt(5) + 2, so x^2 = 5 + 4 + 4sqrt(5) = 9 + 4sqrt(5). Hence x^2 - 4sqrt(5) = 9.