Question

find the 18th term and 23rd term of the A.P -1,5,11,17...

Answer 1

t18=-1+(18-1)×6
=-1+17×6
=-1+102
=101
t23=-1+(23-1)×6
=-1+22×6
=-1+132
=131

Answer 2

#hey there!!

◆Given AP is : -1 , 5 , 11 , 17...

=> common difference (d) = 5-(-1) = 6

=) a = -1

now we know the formula for nth term

=> tn = a + (n-1).d -------(1)

so we have to find 18th term so put n=18 in above formula we get,

=> t(18) = -1 + (18-1)x6

=> = -1 + 17×6

= -1 + 102 = 101 ans.

now we have to find 23rd term : put n= 23 in formula (1) we get,

=> t(23) = -1 +(23-1)×6

=> = -1 + 22×6

=> = -1 + 132 = 131 ans.

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◆hope it will help you