Question

find f(x)=3x^2-21x+19 when f(x) is -1/2

Answer 1

Are you asking for f(-1/2)? If so, there are multiple ways to approach this.

The first is direct substitution. This is where you plug -1/2 in for x directly in the function.
f(-1/2)=3(-1/2)^2-21(-1/2)+19

Another is synthetic substitution. This is where you put the function in the synthetic substitution box and divide by the number you want to evaluate the function for. The remainder is equal to the value of the function for that number.

Answer 2

\[
f(-1/2) = 3(-1/2)^2-21(-1/2)+19
\]

Answer 3

Please explain synthetic substitution.