simplifying (1 Viewer)

[Pinkled]

So i'm doing some induction, and in the back of the book it did this:
http://puu.sh/2bUAQ
can anyone explain how they got from that line to the next please?

 

[funnytomato]

-2a+a=-a , where a=1/2^k

 

[iSplicer]

So i'm doing some induction, and in the back of the book it did this:
http://puu.sh/2bUAQ
can anyone explain how they got from that line to the next please?

The 1/(2^k) is factorised out - so it becomes 2 - 1/(2^k)[2-1] = 2 - 1/(2^k)

Hope that helps!

 

[Drongoski]

-2a+a=-a , where a=1/2^k

i.e. less 2 tomatoes plus 1 tomato = less 1 tomato