To factor the quadratic expression \(-2v^2 + 11v + 21\), we need to find two numbers that multiply to the product of the leading coefficient and the constant term (i.e., \(-2 \times 21 = -42\)) and add up to the middle coefficient (i.e., \(11\)). Once these numbers are found, we can use them to split the middle term and factor by grouping.
Step 1: Identify the Quadratic Expression
We start with the quadratic expression:
\[
-2v^2 + 11v + 21
\]
Step 2: Factor the Expression
To factor the expression, we can rewrite it as:
\[
-(2v^2 - 11v - 21)
\]
Next, we find two numbers that multiply to \(-42\) (the product of \(-2\) and \(21\)) and add to \(11\). The numbers \(14\) and \(-3\) satisfy these conditions.
Step 3: Split the Middle Term
We can split the middle term \(11v\) using \(14v\) and \(-3v\):
\[
-2v^2 + 14v - 3v + 21
\]
Step 4: Factor by Grouping
Now, we group the terms:
\[
(-2v^2 + 14v) + (-3v + 21)
\]
Factoring each group gives us:
\[
-2v(v - 7) - 3(v - 7)
\]
This can be factored further as:
\[
-(v - 7)(2v + 3)
\]
Final Answer
Thus, the completely factored form of the expression is:
\[
\boxed{-(v - 7)(2v + 3)}
\]