Question 15
If $$(1 + xy + x + y)^2 - (1 - xy + x - y)^2 = ky(1 + x)^2$$, then $$k$$ equals to
Solution
Factorising each bracket, $$1 + xy + x + y = (1 + x)(1 + y)$$ and $$1 - xy + x - y = (1 + x)(1 - y)$$. So the left side is $$(1 + x)^2[(1 + y)^2 - (1 - y)^2] = (1 + x)^2 (4y)$$. Comparing with $$ky(1 + x)^2$$ gives $$k = 4$$.
Get AI Help
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
Session:Free CAT Mentorship
Phone:
Date:
Time:
Enter OTP
Didn't receive the OTP?
