The number of real roots of the equation, e 4 x + e 3 x - 4 e 2 x + e x + 1 = 0 is:

The number of real roots of the equation, e4x+e3x-4e2x+ex+1=0 is:
  1. 1
  2. 3
  3. 2
  4. 4

Solution

Let ex=t0,
Given equation
t4+t3-4t2+t+1=0
t2+t-4+1t+1t2=0
t2+1t2+t+1t-4=0
Let t+1t=α
α2-2+α-4=0
α2+α-6=0
α2+α-6=0
α=-3,2α=2ex+e-x=2
x=0 is the only solution.

Asked in: JEE Main 2020 (09 Jan Shift 1)

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