Question

Find value of "y" if sum of AP - 1,4,7,10......Y=287.(solve by factorization)

Answer 1

Sn=287
a=1
d=3
$sn = \frac{n}{2} (a + (n - 1)d) \\ 287= \frac{n}{2} (1 + ( n- 1)3) \\ 287 = \frac{n}{2} (1 + 3n - 3) \\ 287 = \frac{ - 2n}{2} + 3 {n}^{2} \\ 287 = - n + 3 {n }^{2} \\ 3{n}^{2} - n + 287 = 0$
Solve it further by factorization