Question

find out the sum of 34,32,30,...10​

Answer 1

Step-by-step explanation:

a= 34

d = 32-34=-2

an= a + (n-1)d

10 = 34 + (n-1) -2

10-34 = -2(n-1)

-24 = -2(n-1)

12 = n-1

13= n

S = n/2 [2a +(n-1)d]

S= 13/2 [ 2×34 + 12(-2)]

S = 13/2 ( 68 - 24)

S = 13/2 (44)

S = 13 × 22

S = 286

Answer 2

Answer:

286

Step-by-step explanation:

a= 34

d = 32-34=-2

an= a + (n-1)d

10 = 34 + (n-1) -2

10-34 = -2(n-1)

-24 = -2(n-1)

12 = n-1

13= n

S = n/2 [2a +(n-1)d]

S= 13/2 [ 2×34 + 12(-2)]

S = 13/2 ( 68 - 24)

S = 13/2 (44)

S = 13 × 22

S = 286