Question

find the sum of AP in -5+(-8)+(11)+.......+(-230)

Answer 1

$\huge{\mathfrak{Bonjour!!}}$

$\large\green{\mathfrak{Solution:}}$

$\blue{\mathfrak{given:}}$

$\blue{a=-5 \:and \:d=-3}$

let the no. of term be tn

tn=a+(n-1)d=-230

-5+(n-1)-3=-230

-3n+3=-225

-3n=-228

n=76

now,

$sn = \frac{n}{2} (2a + (n - 1)d) \\ \\ \frac{76}{2} ( - 10 + (75) - 3) \\ \\ \\ = > 38×-235=>-18930$

$\large\underline\red{\boxed{\mathfrak{Question\:Error:there \:is\: not \:same\: common\: difference}}}$