Question

find the 12th term from the end of the following AP first 3,5,7,9, .....201

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Answer 1

Step-by-step explanation:

first term a=3

common diff.(d)=2

a12=a+11d

=3+11.2

=25

Answer 2

Answer:

179

Step-by-step explanation:

3, 5, 7, 9 ....... 201

1st method

to find the term from last we write the series in reverse

201, 199, 197..........3

a = 201 d = -2

an = a + (n-1)d

a12 = 201 + (12-1)-2

= 201 + (11×-2)

= 201 - 22

= 179

179 is the 12th term from end.

2nd method

find total number of term where last term is 201

an = a + (n-1)×d

201 = 3 + (n-1)×2

201 - 3 = (n-1)×2

198 = (n-1)×2

n - 1 = 198/2

n - 1 = 99

n = 99 + 1 = 100

there are 100 terms in total

12 term from last Will be the 89th term from first

a89 = 3 + (89-1) × 2

= 3 + 88(2)

= 3 + 176

= 179

hope you get your answer