Flag IIT JEE Entrance Exam> Let S={x:x belongs to R(√3+√2)^(x^2-4) - ...
question mark

Let S={x:x belongs to R(√3+√2)^(x^2-4) - (√3-√2)^(x^2-4)=10}. Then n(S) is equal to-

AskUser , 3 Months ago
Grade
anser 1 Answers
Askiitians Tutor Team

Let t = x^2 - 4.

Let a = √3 + √2. Then √3 - √2 = 1/a (since (√3+√2)(√3-√2) = 3 - 2 = 1).


So the equation becomes:

a^t - a^(-t) = 10.


Let y = a^t > 0.

Then y - 1/y = 10

=> y^2 - 10y - 1 = 0.


Solving, y = 5 ± √26.


But only y = 5 + √26 > 0 is valid.


So a^t = 5 + √26

=> t = ln(5 + √26) / ln(a).


Now, x^2 = t + 4.


Thus there are two real values of x:

x = ±√(t + 4).


Therefore, n(S) = 2.

ApprovedApproved
Last Activity: 3 Months ago
star
LIVE ONLINE CLASSES

Prepraring for the competition made easy just by live online class.

tv

Full Live Access

material

Study Material

removal

Live Doubts Solving

assignment

Daily Class Assignments