Question

Find a1+a6+a11+a16 if it is known that a1, a2,...... Is an

a.P. And a1+a4+a7+.......+a16=147

Answer 1

Answer:

98

Step-by-step explanation:

a1 + a4 + a7 + a10 + a13 + a16 = 147

a2 = a1 +d , a3 = a1 + 2d and so on

a1 + a1 +3d + a1+6d + a1 + 9d + a1 +12d + a1+15d = 147

6a1 + 45d = 147

3(2a1+15d) = 147

2a1 + 15d = 49

a1 + a6 + a11 + a16

= a1 + a1 +5d + a1+10d + a1+15d

= 4a1 + 30d

=2(2a+15d)

= 2 * 49

= 98