JEE Main20241 Feb 2024Morning ShiftMathematicsQuadratic EquationActual
Let S = x ∈ R : 3 + 2 x + 3 − 2 x = 10 . Then the number of elements in S is:
Options
- A4
- B0
- C2
- D1
Correct answer
C. 2
Step-by-step solution
Given: 3 + 2 x + 3 - 2 x = 10 Now, let 3 + 2 x = t ⇒ 3 - 2 x = 1 t So, 3 + 2 x + 3 - 2 x = 10 ⇒ t + 1 t = 10 ⇒ t 2 - 10 t + 1 = 0 ⇒ t = 5 ± 2 6 ⇒ t = 3 - 2 2 , 3 + 2 2 Now, taking 3 + 2 x = 3 - 2 2 = 3 + 2 - 2 we get, x = - 2 And equating 3 + 2 x = 3 + 2 2 we get, x = 2 Hence, the number of elements in S is 2