Question

4+7+10+13+..............sum of the 12 terms of this A.Pis​

Answer 1

4 + 7+ 10 + 13 + .....

a = 4 , d = a2 - a1 , n = 12 , S12 = ?

d = 7 - 4

d = 3

Sn = n/2 {2a +(n - 1) d}

S12 = 12/2 {2(4) + (12 - 1)3}

S12 = 6 {8 + 11(3)}

S12 = 6{8 + 33}

S12 = 6{41}

S12 = 246

So the sum of 12 terms of an A.P 4+7+10+13+...... is 246