Solution:
Given equation, 4x²-3px+9=0
where, a = 4, b = -3p, c = 9
Since roots are real,
So, b² - 4ac ≥ 0
(-3p)² - 4 x 4 x 9 ≥ 0
9p² – 144 ≥ 0
9p² ≥ 144
p² ≥ 144/9
p² ≥ 16
p² ≥ 4²
p ≥ ±4
The value of p so that the equation 4x²-3px+9=0 has real roots is p ≥ 4 or p ≥ - 4.