1) 380 +80х=1500-60х
х=8
2) (1;9), (-20; -33), (43; 93)
3) (10;6 ), (50; 10), (120; 17) кажется, как то так)
(sin²a/2-cos²a/2)(sin²a/2+cos²a/2)==cosa*1=-cosa
-cosa=-cosa
А) sin(45+30)=sin45cos30+sin30cos45=sqrt(2)/2*sqrt(3)/2+1/2*sqrt(2)/2=(sqrt(3)+1)/(2*sqrt(2))
б) cos(135/2)=sqrt((1+cos135)/2)=sqrt{(1-sqrt(2)/2)/2}=sqrt((2-sqrt2)/4)=(sqrt(2-sqrt2))/2
(x^2+рi^2/4+pix-pi^2/4)(cosx-sinx)=0 cosx>=sinx
<span>98х6-2z</span><span><span>^</span>2=2(49x^6-z</span><span>^2)=2(7x</span><span>^3-z)(7x</span><span>^3+z)</span>