Particles P1 and P2 are located in three dimensional space at the points (2.00, -3.50, 1.75) mm and (-3.50, 2.25, -2.00) mm. These particles carry charges of +3.00 μC and +4.50 μC respectively. What is the magnitude of the net force they exert on another particle P3, with charge -3.50 μC, located at the origin?