Question

Помогите плиз40балллоов дам

Answer 1

7) a7 = 16, a9 =30

a9 = a7 + d + d

30 = 16 + 2d

d = 7

a8 = a7 + d

a8 = 23

5) a1 = 28, a21 = 4

a21 = a1 + 20d

20d =4 - 28 = -24

d = -24/20

6) b5 = b1 * q * q * q * q

4) b4 = b2 * q * q

9 = 4 * q^2

q^2 = 9/4

q = 3/2, так как bn > 0