305.060-305-129.352+106•1.200+870.580:
:290=305.605
1) 106•1.200=127.200
2) 870.580:290=3.002
3) 305.060-305=304.755
4) 304.755-129.352=175.403
5) 175.403+127.200=302.603
6) 302.603+3.002=305.605
2х-19=8-х
2х+х=8+19
3х=27
х=27:3
х=9.
Ответ: х=9.
{♣}.
4) (m-124)+316=900
m-124+316=900
m+192=900
m=900-192
<span>m=708</span>
<span> Решение:
sin^3a(1+ctga)+cos^3a*(1+tga)=(1+cosa/sina)sin^3a+cos^3a(1+sina/cosa)=
=(sina+cosa)(sin^2a+cos^2a).</span>