Question

What is the missing constant term in perfect square that starts with x2+14x?

Answer 1

we know that

A perfect square is (x+a)²---------> x²+2ax+a²
if we have  x²+14x
then
2ax=14x-----------> 2a=14--------a=7

therefore
a²=7²----> 49
x²+2ax+a²------> x²+14x+49

the answer is
49