1.

Find the cube of 5 is to 2 by 7

Answer» SINCE, other solution have described the PROCEDURE nicely,I will just briefly go through that and then add something extra.

1)call each TERM as a or b

2) Find a3a3,b3b3 and abab

3)Use (a+b)3(a+b)3 =a3+b3+3ab(a+b)a3+b3+3ab(a+b) identity.

You know EVERYTHING in the last equation,except a+b which you can solve and find.

EXTRA:

One notices by OBSERVATION that (7+52–√)1/3=1+2–√(7+52)1/3=1+2

(7−52–√)1/3=1−2–√(7−52)1/3=1−2

Hence the sum =(1+2–√)+(1−2–√)(1+2)+(1−2)

                           =22

Hence solved.


Discussion

No Comment Found

Related InterviewSolutions