Answer:
1
Step-by-step explanation:
The constant term in a perfect square trinomial with leading coefficient 1 is the square of half the coefficient of the linear term.
(2/2)² = 1
The missing constant term is 1.
(x-3)^2 + (x+5)^2=9^2
(x^2-6x+9) + (x^2+10x+25)=81
2x^2+4x+34=81
2x^2+4x-47=0
From here just use quadratic formula
The answer would be 13.9 kg of gravel used per square meter