How do you evaluate the function $f(x) = -x^2 + 3x-1$ for $f(-1)$ ?

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Answer 1 · 2015-11-06T20:30:03

The most obvious way is to replace the $x$ 's in the expression with $(-1)$ and evaluate using normal arithmetic.

If $f(color(blue)(x)) = -color(blue)(x)^2+3color(blue)(x) -1$
then
$color(white)("X")f(color(red)((-1)))= -color(red)((-1))^2+3color(red)((-1))-1$

$color(white)("XXXXXXX")= -1 -3 -1$

$color(white)("XXXXXXX")= -5$

How do you evaluate the function f(x) = -x^2 + 3x-1f(x) = -x^2 + 3x-1 for f(-1)f(-1)?