Answer
Possible values of b:
$3,\ 4$
(note, if b=0, the polynomial can be factored, but then it is a binomial, not a trinomial)
Work Step by Step
If the trinomial $x^{2}+4x+b$ can be factored, it will be in the form $(x+n)(x+m)$, where
the product of integers n and m is $b$
their sum is $4.$
4 is positive, both factors of b are positive .
$\left[\begin{array}{lll}
\text{sum=4} & \text{product = b} & \\
0+4 & 0 & \\
1+3 & 3 & \\
2+2 & 4 &
\end{array}\right]$
possible values of b:
$3,\ 4$
(note, if b=0, the polynomial can be factored, but then it is a binomial, not a trinomial)