Question

the sum of the first 10 negative even numbers
formula = Sn = n/2 (2n + (n- 1 ) d)​

Answer 1

Step-by-step explanation:

n=10

d= -4-(-2)= -4+2= -2

a= -2

Sn = 10/2(2(-2)+(10-1)(-2))

=5(-4+(9×-2))

=5(-4-18)

=5×-22

= -110

Answer 2

Answer:

first 10 negative even numbers =

- 2 , - 4 , -6 , -8 , - 10 , -12, -14, -16, -18, -20

formula of sn = n/2 { (2a + (n-1 )d

• d = a1 - a

a2 - a1

-4 - ( -2)

= - 4 + 2

= - 2

• common difference. = -2
• a = -2
• n = 10

Sn = n/2 { ( 2a + (n - 1 ) d }

Sn = 10 / 2 { 2 × -2 + ( 10 - 1 ) × -2

Sn = 5 { ( - 4 + ( 9 × -2 ) }

Sn = 5 { ( -4 - 18 ) }

Sn = 5 × -22

Sn = -110

hopes it will help you