Question

Find that 10th term of each arithmetic sequence

1). A4=12 and A7=20.4

2.) A3=37 and A17=-12

3.) A13=-5 and A18=-51

4.) A25=18 and A41=62

Answer 1

1.

4th term = a1 + 3d = 12 (where a1 = first term and d = common difference.)

7th term = a1 + 6d = 20.4

subtract 4th from 7th term, we get:-

3d = 8.4

d = 2.8

So 10th term = 7th term + 3(common difference)

= 20.4 + 3(2.8)

= 20.4 + 8.4

= 28.8 (answer)

All the rest can be answered in the same way.