Sign in
Please select an account to continue using cracku.in
↓ →
Given '$$y$$' is a natural number, how many values of "$$y$$" are possible for $$(y^2 - 5y + 5)^{(y - 8)(y + 6)} = 1$$?
Expression : $$(y^2 - 5y + 5)^{(y - 8)(y + 6)} = 1$$
=> $$log(y^2 - 5y + 5)^{(y - 8)(y + 6)} = log(1)$$
=> $$(y-8)(y+6)log(y^2-5y+y)=0$$
Thus, either $$(y-8)=0$$ or $$(y+6)=0$$ or $$log(y^2-5y+5)=0$$
=> $$y=8,-6$$ ---------------(i)
or $$log(y^2-5y+5)=log(1)$$
=> $$y^2-5y+4=0$$
=> $$(y-4)(y-1)-0$$
=> $$y=4,1$$ -----------(ii)
Also, $$y^2-5y+5$$ can be equal to -1, and the power will be even; thus, it can be equal to 1.
$$y^2-5y+5$$ = -1
$$y^2-5y+6$$ = 0
y = 2 or 3
When y = 2, power will be(y-8)(y+6) = -48 even power, hence = 1
When y = 3, power will be 45 odd power, hence = -1
Thus, y = 2 also satisfies the condition.
From equations (i) and (ii), Possible values of $$y$$ (natural number) = 4
=> Ans - (A)
Was this solution helpful?
Click on the Email ☝️ to Watch the Video Solution
Create a FREE account and get:
Book Free CAT Mentorship
Get personalized CAT strategy from a 99%iler
500+ students mentored
OTP Verification
Enter the 6-digit code sent to your phone
Booking Summary
Enter OTP
Didn't receive the OTP?
Start your IIM journey with the right preparation and crack CAT 2026.
Educational materials for CAT preparation