Question

Let a1, a2, a3.....a18 are in A.P. and a1 =5. if a1 + a6 + a8 + a11 + a13 + a18 = 180, then the value of a18 is​

Answer 1

Hey mate here is your answer::

as a1= 5

and we know that:: an = a + (n-1)d

so,,,according to the ques; {a1=a }

a1 +a6 + a8 +a11 +a13 +a18 = 180

a1 + a + 5d + a +7d + a + 10d + a+ 12d +a + 17d = 180

6a + 51d =180

6 × 5 + 51d= 180

51d = 180-30

d = 150/ 51

Now,,a18 = a +17 d

= 5 + 17 × 150/51

=5 + 2550/51

= 5 + 50

= 55

Hope it helps u...Have a good day...

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