InterviewSolution
Saved Bookmarks
| 1. |
If `x` is real then the value of `(x^2 - 3x +4) / (x^2 + 3x +4)` lies in the intervalA. `(0, 1//7)`B. `7, oo)`C. `[1//7, 7]`D. `[-1//7, 7]` |
|
Answer» Correct Answer - C Let `y = (x^(2)-3x + 4)/(x^(2) + 3x + 4)`. Then, `x^(2) (y-1) + 3x(y+1)+4(y-1) = 0` This equation gives the values of x for given values of y. But, y is the value when x is real. So, the roots of this equaton are real. `therefore" "9(y+1)^(2) - 16(y-1)^(2) ge 0" "["Using Discriminant" ge 0]` `rArr" "7y^(2) - 50y + 7 le 0 rArr (7y-1) (y-7) le 0 rArr 1//7 le y le 7`. Hence, the given expression lies between 1/7 and 7. |
|