AP EAMCET201921 Apr 2019Evening ShiftMathematicsQuadratic EquationActual
x ∈ ℝ : 6 + x - x 2 2 x + 5 ≥ 6 + x - x 2 x + 4 =
Options
- A[ - 2 , 3 ]
- B( - ∞ , - 4 ] ∪ - 5 2 , - 1
- C[ - 2 , - 1 ] ∪ 3
- D( - ∞ , - 4 ] ∪ [ - 2 , - 1 ]
Correct answer
C. [ - 2 , - 1 ] ∪ 3
Step-by-step solution
It is given that, 6 + x - x 2 2 x + 5 ≥ 6 + x - x 2 x + 4 Rewrite the above equation. ⇒ 6 + x - x 2 1 2 x + 5 - 1 x + 4 ≥ 0 ⇒ 6 + x - x 2 x + 4 - 2 x - 5 ( 2 x + 5 ) ( x + 4 ) ≥ 0 ⇒ 6 + x - x 2 - ( x + 1 ) ( 2 x + 5 ) ( x + 4 ) ≥ 0 ⇒ ( x + 1 ) ( 2 x + 5 ) ( x + 4 ) ≤ 0 Now, x ∈ ( - ∞ , - 4 ) ∪ ( - 5 2 , - 1 ]     . . . i For the expression to exist 6 + x - x 2 ≥ 0 ⇒ x 2 - x - 6 ≤ 0 ⇒ ( x - 3 ) ( x + 2 ) ≤