f(x) = x^2-5x +3.
We proceed
to show that the right side of this equation can be a square expression minus a
constant.
Let f(x) = (x-k)^2 - k^2+3
.
We choose , k sich that 2kx = -5x. So that k =
-5.
Therefore f(x) = (x-5/2)^2 - (5/2)^2+3 =
0.
f(x) = (x-5/2)^2 - 25/4 + 3 =
0,
f(x) = (x-5/2)^2 - 13/4 =
0.
Therfore f(x) = a square expression minus 13/4. The
right side is minimum when square expression (x-5/2)^2 is zero. Otherwise the squre
expression being positive, f(x) > = -13/4 for all
x.
So f(x) is minimum when x= 5/2 and the minimum f(x) =
f(5/2) = -13/2. So x = is the value when f(x) at the lower extreme. f(x) grows to
infinity as x--> infinity. As such, there is no upper extreme
value.
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