Answer:
-63
Explanation:
Compare ...
f(x) = x^2 -3x +18
to the standard form ...
f(x) = ax^2 +bx +c
and you will see that ...
a = 1, b = -3, c = 18.
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The value of the discriminant is ...
d = b^2 -4ac
d = (-3)^2 -4(1)(18) = 9 -72 = -63
The discriminant is -63.