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prove that 7 + 77 + 777 +...... + 777.....

prove that `7 + 77 + 777 +...... + 777........._(n-digits) 7 = 7/81 (10^(n+1) - 9n - 10)` for all `n in N`

A

a=1,b=9,c=9

B

a=1,b=9,c=10

C

a=1,b=-9,c=-10

D

a=1,b=-9,c=-10

Text Solution

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The correct Answer is:
B
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AAKASH INSTITUTE-PRINCIPLE OF MATHEMATICAL -Section-B((Objective Type Questions (One option is correct))
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