or, n^2+5n+7-7 = 7-7 ( Subtracting 7 from both sides)
or, n^2+5n = 0
or, n(n+5) = 0
or, n=0 or n= -5
C)
2t^2-14t+3 = 3
or, 2t^2-14t = 0
or, 2t(t-7) = 0
or, t=0 or t=7
D)
1/3x^2+3x-4 = -4
or, 1/3x^2+3x = 0
or, 1/3x(x+9) = 0
or, x=0 or x= -9
E)
Zero is a common solution to each of the equations. This is because each of the equations had a variable outside the parenthesis with an operation of multiplication.
I would say D.) is the best choice in this situation, The amount of female children you have does not determine the Gender that your child will be, The kids have nothing to do with the situation, The Father and Mother are what determine the Gender.