Answer:
-7.5
Explanation:
The standard form of a quadratic eqaution is expressed as;
f(x) = ax^2+bx+c
Given the quadratic equation f(x) = x^2 + 15x + 3
on comparison;
a = 1, b = 15 and c = 3
The equation of the axis of symmetry for this function is expressed as;
x = -b/2a
Substitute the given values
x = -15/2(1)
x = -15/2
x = -7.5
Hence the equation of the axis of symmetry for this function is 7.5
