RRB Junior Engineer / DMS / CMA 2015 · Question 24 of 480

All values of k for which x2 -kx + 9 = 0 has real roots is

Mathematics - Quadratic Equations

Aa. - 6 < k< 6
Bb. 6 < k<- 6Correct
Cc. k>6
Dd. k<-6

Answer: B. b. 6 < k<- 6

Explanation

Given equation, x2 - Kx + 9 = 0 Comparing the given Eq. from ax2 + fax + c = 0 a = 1,b = -K, c = 9 v roots are real b2 - 4ac > 0 => (-K)2 - 4 x 1 x 9 > 0 => K2 > 36 => 6 < K < -6

Source: Arihant RRB JE Solved Paper 26-Aug-2015 (3rd Shift), Q91–150 — published solved-paper compilation (Q1–90 technical not included in this source) · memory-based

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