a+b=9m এবং ab=18m2 হলে a-b= ?
A
3m
B
-3m
C
6m
D
8
Correct Answer: 3m
a + b = 9m এবং ab = 18m2 ∴ a - b2 = a + b2 - 4ab = 9m2 - 4 × 18m2 = 9m2 = ±3m2∴ a - b = ±3m