1)3,5-9a=a-8
-9a-a=-8-3.5
-10a=-28
a=2.8
2)3(2.4-1.1m)=2.7m+3.2
7.2-3.3m=2.7m+3.2
-3.3m-2.7m=3.2-7.2
-6m=-4
m=1.5
2х+3=0;
2х=0-3;
2х=-3;
Х=-3:2;
Х=-1,5.
(sina+sinb)^2+(cosa+cosb)^2=sina^2+2sina*sinb+sinb^2+cosa^2+2cosa*cosb+cosb^2=<span>=1+1+2sina*sinb+2cosa*cosb=2+2cos(a-b)=2(1+cos(a-b))</span>