Mathematics
If (k + 2)x2 - 2x + 1 = 0 has real roots then greater value of k(∈ Z) is :
1
3
-1
none of these
Answer
Given,
Equation : (k + 2)x2 - 2x + 1 = 0
Comparing (k + 2)x2 - 2x + 1 = 0 with ax2 + bx + c = 0 we get,
a = (k + 2), b = -2 and c = 1.
Since, roots are real,
∴ D ≥ 0
⇒ b2 - 4ac ≥ 0
⇒ (-2)2 - 4(k + 2)(1) ≥ 0
⇒ 4 - 4(k + 2) ≥ 0
⇒ 4 - 4k - 8 ≥ 0
⇒ -4k - 4 ≥ 0
⇒ 4k ≤ -4
⇒ k ≤ -1.
Thus, greatest value of k = -1.
Hence, option 3 is the correct option.