Answer:
1
Explanation:
The quadratic relation is a perfect square:
y = (7x +3)²
so has one zero, where the factor is zero:
7x +3 = 0
7x = -3
x = -3/7
_____
It is useful to have handy reference to the form of the square of a binomial:
(a +b)² = a² +2ab +b²
Here, your first clue is that 49x² and 9 are both perfect squares: (7x)² and (3)². It is easy to check that the middle term is twice the product of these roots:
2(7x)(3) = 42x . . . . matches the middle term
So, the given expression is equivalent to ...
y = (7x +3)²