1. The problem is to express the quadratic expression $x^2 + 14x + 49$ in the form $(x + a)^2$. 2. Recall the formula for a perfect square trinomial: $$(x + a)^2 = x^2 + 2ax + a^2$$ 3. We need to find $a$ such that $2a = 14$ and $a^2 = 49$. 4. Solving $2a = 14$ gives $a = 7$. 5. Check $a^2 = 7^2 = 49$, which matches the constant term. 6. Therefore, the expression can be written as $$(x + 7)^2$$. Final answer: $$(x + 7)^2$$.