x^2+14x
To make it as perfect square binomial first divide the numerical coefficient of 14 by 2 which is 7. Then square the result[7] which is 49 and add it to the equation
x^2+14x+49
After that think of a number that has a square root of 49 then when u multiply the second term in the perfect square by the first and 2 it results to 14. So the answer is
[x+7]^2