A little math help please?

Question

Find f(x + ∆x) for f(x) = x² - 2x - 3

What exactly does f(x + ∆x) mean?

Answer 1

the triangle means "change in <given variable>"

Answer 2

To find f(3), plug in 3 everywhere you see x in the original equation.

To find f(2x), plug in 2x everywhere you see x in the original equation.  

f(x + ∆x) means everywhere you see x in the original equation, plug in x + ∆x

f(x + ∆x)=(x + ∆x)²-2*(x + ∆x)-3

=x²+2x∆x+∆x²-2x-2∆x-3

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