Given
... f(x) = x² -4x +1
Find
... a) f(-8)
... b) f(x+9)
... c) f(-x)
Solution
In each case, put the function argument where x is, then simplify.
a) f(-8) = (-8)² -4(-8) +1 = 64 +32 + 1 = 97
b) f(x+9) = (x+9)² -4(x+9) +1
... = x² +18x +81 -4x -36 +1
... f(x+9) = x² +14x +46
c) f(-x) = (-x)² -4(-x) +1
... f(-x) = x² +4x +1
