Found on Reddit but still don't understand!

GRE Quant Problem Solving
1

From official GRE Quant book:

Can someone please explain why “Substituting for B” is NOT 2^4 + 2^7?

Thank you!
Quant

2

It’s 2^4 - (-7)^4. Expand the brackets first: (-7)^4 = 7^4. Hence 2^4 - (7)^4

3

Thank you for the response!

So, if the (-7) was raised to an odd numbered power, it would remain negative?

4

Correct.

5

Thank you!