Question

can anyone help me with this questions l have test on this today fast Please ​

Answer 1

Explanation:

16)

a17 = a10+ 21

a + 16d = a + 9d + 21

16d - 9d => 21

7d = 21

d = 3

17)

a7 = a + 6d

4 = a + 6 * -4

4 = a - 24

a = 28

sorry but i can't see the question 18 properly

19)

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

406 = n/2 [ 6 + (n-1). 4]

812 = n [ 6+ 4n -4]

812 = n [ 4n +2]

812 = 4n^2 + 2n

you can factorize it easily you will get your answer

hope it will help you

Answer 2

Answer:

i dont know the amswer ok