Answer
$$x^2+14x+49$$
Work Step by Step
Multiplying the equation out, we find:
$$x^2+2x\cdot \:7+7^2\\ x^2+14x+49$$
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.