?
If a = 4011 and b = 3989, then value of ab = ?
Answer & Solution
Correct Answer:
Option
A
a = 4011
b = 3989
a × b = 4011 × 3989
= 15999879
Shortcut method :
a = 4011 ⇒ (4000 + 11)
b = 3989 ⇒ (4000 - 11)
[(a - b) (a + b) = a2 - b2]
According to the question,
a × b = (4000 + 11) (4000 - 11)
= 40002 -112
= 16000000 - 121
= 15999879
b = 3989
a × b = 4011 × 3989
= 15999879
Shortcut method :
a = 4011 ⇒ (4000 + 11)
b = 3989 ⇒ (4000 - 11)
[(a - b) (a + b) = a2 - b2]
According to the question,
a × b = (4000 + 11) (4000 - 11)
= 40002 -112
= 16000000 - 121
= 15999879
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