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

1 Answer
Alan P.
Nov 6, 2015

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

Explanation:

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#

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