Здравствуйте решить умоляю во жизни и смерти..

1) 2^5 * 2^3 = 2^8 = 256

2) 7^10 : 7^8 = 7^2 = 49

3) 19^1 * 19^7/19^8 = 19^8/19^8 = 1

4) 21^9 : 21^8/21 = 21^1/21 = 1

5) (3^5)^6 : 3^10 = 3^30 : 3^10 = 3^20

6) 3^6 * 3^10 : 3^14 = 3^2 = 9

7) (7^5)^6 : (7^4)^7 = 7^30 - 7^28 = 7^2 = 49

х-4 / х + 4 = 2

х-4 / х = 2 - 4

х-4 / х = -2

-2х = х-4

-2х-х= -4

-3х= -4

х = 4/3

х = 1 1/3

s=pi*r^2

r^2=s/pi

r=sqrt(s/pi)