0,4y - 1 = 0
0,4y = 1
y = 1/0,4 = 2,5
2 + y = 0
y = - 2
y^2 + 2 = 0
y^2 = - 2
реш. нет
[(cosa+cos7a)-(cos10a+cos4a)]/[(sina+sin7a)+(sin10a+sin4a)]=
=(2cos4acos3a-2cos7acos3a)/(2sin4acos3a+2sin7acos3a)=
=2cos3a(cos4a-cos7a)/[2cos3a(sin4a+sin7a)]=
=2sin5,5asin1,5a/(2sin5,5acos1,5a)=sin1,5a/(cos1,5a)=tg1,5a
<span>(123+375)*24:(212-129)=</span>11,952/83=144