SOLUTION: if f(x)=x^2-7x find f(a+1)-f(a)

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Question 405550: if f(x)=x^2-7x find f(a+1)-f(a)
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
f(x)=x^2-7x
f(a)=a^2-7a
f(a+1)=(a+1)^2-7(a+1)=a^2+2a+1-7a-7=a^2-5a-6

So f(a+1)-f(a) = a^2-5a-6 - (a^2-7a) = a^2-5a-6-a^2+7a = 2a-6

or in short f(a+1)-f(a) = 2a-6


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