Question

which term of the ap: -2,-7,-12,--- will be -77? find the sum of this ap upto the term -77.

Answer 1

Answer:

Step-by-step explanation:

Answer 2

Answer:

Sn -483

Step-by-step explanation:

AP = -2, -7, -12,..........-77

a = -2,d = -5

an = -77, an = a+(n-1)xd

a+(n-1)xd = -77

-2+(n-1)x -5 = -77

(n-1)x -5 = -77 + 2

(n-1) + -75/-5

(n-1) = -13

n = 13 +1

n = 14

Sn = n/2(2a+ (n-1)xd)

sn =14/2{2(-2)+(14-1x-5)}

=7{(-4)+13x(-5)}

=7{(-4)+(-65)}

=7{-4-65}

=7x(-69)

=-483

Step-by-step explanation: