SOLUTION: If f(x) = x^2 - 6x find: f(a+1)-f(a) =

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Question 653072: If f(x) = x^2 - 6x 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 - 6x

f(a) = a^2 - 6a

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f(x) = x^2 - 6x

f(a+1) = (a+1)^2 - 6(a+1)

f(a+1) = (a+1)(a+1) - 6(a+1)

f(a+1) = a^2 + 2a + 1 - 6a - 6

f(a+1) = a^2 - 4a - 5

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f(a+1) - f(a)

a^2 - 4a - 5 - (a^2 - 6a)

a^2 - 4a - 5 - a^2 + 6a

2a - 5

So f(a+1) - f(a) = 2a - 5