Answer:
ab = 144
Step-by-step explanation:
Assuming you mean a² + b² = 612, then
(a + b)² = a² + 2ab + b² , that is
30² = a² + 2ab + b² , so
a² + 2ab + b² = 900
a² + b² + 2ab = 900 ← substitute a² + b² = 612
612 + 2ab = 900 ( subtract 612 from both sides )
2ab = 288 ( divide both sides by 2 )
ab = 144
