Is my answer book wrong?

Malfix25

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May 11, 2020
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So, my math homebook has the following exercise: 2n - 3b2n - 2(b2 - 25 - nb)

When I work out the problem, this is the answer I get: 2n - 3b2n - 1 - 42b2n - 1 (Which is equal to 2n - 3b2n - 1 - 16b2n - 1)

But, the solution key to my book shows that this is the answer:

2n - 3b2n - 1 - 4b2n - 1

So, did my answer book make a mistake, or am I the one doing so?
 
So, my math homebook has the following exercise: 2n - 3b2n - 2(b2 - 25 - nb)
When I work out the problem, this is the answer I get: 2n - 3b2n - 1 - 42b2n - 1 (Which is equal to 2n - 3b2n - 1 - 16b2n - 1)
But, the solution key to my book shows that this is the answer:
2n - 3b2n - 1 - 4b2n - 1
So, did my answer book make a mistake, or am I the one doing so?
2n-3 * 25-n =2n-3+5-n = 22

The answer book is correct
 
Oh duh! :oops: My mistake lay where I multiplied the 2n-3 * 25-n, I multiplied the coefficients as well, and got 42, instead of 22 Man it's been too long! Never would have thought I would have forgotten something so fundamental. I guess the saying "use it or lose it" is true!? Thanks man!
 
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