Х=554-291 х=263
еще х-56=291 реши
340х-832=18208
340х=18208+832
х=19040:340
х=56
Sin^2a(1+tg^2a)*ctga=(1/cos^2a)*sinacosa=sina/cosa=tga
(sin^2t-1+tg^2tcos^4t)/cos^4t=(sin^2t-1+cos^2tsin^2t)/cos^4t=(sin^2tcos^2t-cos^2t)/cos^4t=
=(sin^2t-1)/cos^2t=-cos^2t/cos^2t=-1
(-0,14+0,18-0,23)b+1.1
-0.19b+1.1
если b=-10
1,9+1,1=3
В)(1728-729):3=999:3=333
г)1296+81=1377