a+b=9m এবং ab=18m হলে, a-b=?
A
3m
B
-3m
C
6m
D
8m
Correct Answer: 3m
ব্যাখাঃ ( a - b)2 = ( a + b) 2 - 4ab = (9m)2 - 4×18m = 81m2 - 72m a - b = + - 3m