Answer
12.25
Work Step by Step
The coefficient of x is 7.
Adding the square of half the coefficient creates a perfect square.
$(7\div2)^2=3.5^2=12.25$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.