Tolong dijawab dong please.....

Q1 = 4 mikro coulomb = 4×10⁻⁶ C
Q2 = 5 mikro coulomb = 5×10⁻⁶ C
k = 9×10⁹ Nm²C⁻²
F = 450 N
r = ?

r² = k Q1 Q2 / F
r² = 9×10⁹ . 4×10⁻⁶ . 5×10⁻⁶ / 450
r² = 180×10-³ / 450
r² = 0,4×10-³
r² = 4×10-²
r = √4×10-²
r = 2×10-¹
r = 0,2 meter