InterviewSolution
Saved Bookmarks
| 1. |
Let `f(x) =ax^(2) + bx + c and f(-1) lt 1, f(1) gt -1, f(3) lt -4 and a ne 0`, thenA. `a gt 0`B. `a lt 0`C. sign of a cannot be determinedD. none of these |
|
Answer» Correct Answer - B We have, `f(-1) lt 1, f(1) gt -1 and f(3) lt -4` `rArr" "a-b+c lt 1" "...(i)` `rArr" "a+b+c gt -1" "...(ii)` `rArr" "9a + 3b + c lt -4" "...(iii)` From (ii), we have `-a -b -c lt 1" "...(iv)` Multiplying (i) by 3 and adding to (iii), we get `12a + 4c lt -1 rArr 3a + c lt -(1)/(4)" "...(v)` Multiplying (iv) by 3 and adding to (ii), we get `6a - 2c lt -1 rArr 3a - c lt -(1)/(2)" "...(vi)` Adding (v) and (vi), we get `6a lt -(3)/(4) rArr a lt -(1)/(8) rArr a lt 0`. |
|