KVPY2016MathematicsQuadratic Equation
Suppose a is a positive real number such that a⁵-a³+a=2 . Then
Options
- Aa⁶ < 2
- B2 < a⁶ < 3
- C3 < a ⁶ < 4
- D4 a ⁶
Correct answer
C. 3 < a ⁶ < 4
Step-by-step solution
a⁵-a³+a=2 ; a R⁺ Let f ( a )= a ⁵- a ³+ a -2 ; Note . f ( a )>0 a R for a⁶=3 a=3^ 1 / 6 =1.2 use calculator we get f (1.2) 0 so one root in a (3,4)