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criszerriny
- Junior | Next Rank: 30 Posts
- Posts: 19
- Joined: Mon Apr 20, 2009 2:25 pm
criszerriny wrote:What is the value of A^4-B^4?
1. A^2-B^2=16
2. A+B=8
C
1. (a-b)(a+b)=16
some may try (A^2-B^2)^2 but that would fetch a term (2A^2*B^2) which we dont know
Insuff
2. A+B ..again we cannot get A^4-B^4
Together, a+b=8, a-b=2
solve to get a and b, and get A^4-B^4
