Исходное не пишу
<em>х²</em>+18х+81+<em>х²</em>-22х+121<em>-2х²</em>=0
-4х=-202
х=50,5
корень один
A25=a1+24d=-2+24*5=118 , an=a1-(n-1)*d
(1 24/25)^5 * 5^11/7^10=
=((49/25)^5 * 5^11)/7^10=
=(7^10/5^10*5^11)/7^10=
=(7^10*5)/7^10=
=5
8x+3=1-(2x+4)
8x+3=1-2x-4
8x+2x=1-4-3
10x = -6
x = -0.6