2020 · Q3
If the roots of the quadratic equation x² − 4x − log₁₀N = 0 are real, then what is the minimum value of N?
Elementary MathematicsAlgebra
- A1
- B1/10
- C1/100
- D1/10000
Explanation
Real roots need discriminant >= 0: 16 + 4*log10(N) >= 0, so log10(N) >= -4, i.e. N >= 10^-4 = 1/10000. The minimum value of N is therefore 1/10000, option (D).