Complete the square and then factor.
x^2+4x=7

The first term is,  x2  its coefficient is  1 .
The middle term is,  +4x  its coefficient is  4 .
The last term, "the constant", is  -7 

Step-1 : Multiply the coefficient of the first term by the constant   1 • -7 = -7 

Step-2 : Find two factors of  -7  whose sum equals the coefficient of the middle term, which is   4 .
     -7   +   1   =   -6     -1   +   7   =   6