A3+a7=a1+2d+a1+6d=2a1+8d=-12⇒a1+4d=-6⇒a1=-6-4d
S10=(2a1+9d)*10/2=(-12-8d+9d)*5=-60+5d
(2^-4)^-2/2^-10
=2^8/2^-10=2^18
А) (5^4 x 125)/25^2=(5^4 x 5^3)/5^4=5^3=125
<span>(3-x)(2+x)-(4-x)(3+x)=5-x,
6+3х-2х-х</span>²-(12+4х-3х-х²)=5-х,
6+3х-2х-х²-(12+х-х²)=5-х,
6+3х-2х-х²-12-х+х²=5-х,
6+3х-2х-12=5,
-6+х=5,
х=5+6,
х=11.
Ответ: 11.