Question

Find the sum (-5)+(-8)+(-11)+...+(-230)

Answer 1

Answer:

$\huge{\boxed{\boxed{\sf{S76=-8930}}}}$

Step-by-step explanation:

$\huge{\boxed{\boxed{\underline{\sf{SOLUTION-}}}}}$

□a1= -5

□d=a2-a1

= -8+5

= -3

□an= -230

$an = a + (n - 1)d \\ = ) - 230 = - 5 + (n - 1) \times - 3 \\ = ) - 230 + 5 =( n - 1) \times - 3 \\ = ) - 225 =( n - 1) \times - 3 \\ = ) \frac{ - 225}{ - 3} = n - 1 \\ = )75 = n - 1 \\ = )n = 75 + 1 \\ = )n = 76$

□n= 76

_________________________________________

$sn = \frac{n}{2} (a + an) \\ \: \: \: \: \: \: = \frac{76}{2} ( - 5 - 230) \\ \: \: \: \: \: \: = 38( - 235) \\ \: \: \: \: \: \: = 38 \times - 235 \\ \: \: \: \: \: \: = - 8930$

$\huge{\boxed{\boxed{\sf{S76=-8930}}}}$

_________________________________________