Answer:
This is a perfect square trinomial of the form `(ax + b)² = a²x² + 2abx + b²`.
In this case, we have `4x² + ___x + 49`.
We can take half of the middle term and square it to find the missing term.
The middle term is `2abx`, so `2ab = x`.
We can see that `a = 2` and `b = 7`, so `2(2)(7) = 28`.
Therefore, the missing term is `28x²`.
So the complete trinomial is `4x² + 28x + 49`.
Step-by-step explanation: