What type of convergent plate boundary is found in the western pacific ocean east of australia where the mariana's trench is as much as 35,000 feet below sea level?

Ocean-Coverget is one of the type of convergent plate boundary is found in the western pacific ocean east of australia where the mariana's trench is as much as 35,000 feet below sea level. Ocean convergent or oceanic-oceanic convergent plate boundaries is defined as when one Oceanic plate subducts another Oceanic Plate forming volcanic islands and trenches.

2. x2 + 8x + 12 = 0 to prove: x = -6 or x = -2