Х+у=-4 *5
5х-4у=16
5х+5у=-20
5х-4у=16
5у+4у=-20-16
9у=-36
у=-4
х=-4-у=-4+4=0
<span>(sin5cos15 + cos5sin15)\(cos80cos150 + Sin80sin150) =
= sin(5 + 15) / cos(80 - 150) = sin20/sin70 = sin20/sin(90 - 20) =</span>
= sin20/cos20 = tg20
10a + sqrt(-35+12x-x^2)=ax+1
Sqrt(-35+12x-x^2)=ax+1-10a
-35+12x-x^2=a^2+2(1-10a)x+(1-10a)^2
X^2+(2-10a-12)x+35+(1-10a)^2=0
X^2-10(a+1)x+(36-20a+100a^2)=0
D=0
100(a^2+2a+1)-4(36-20a+100a^2)=0
-300a^2+280a-44=0
-75a^2+70a-11=0
D=4900-4*75*11=4900-3300=1600
A=(-70-40)/-150=11/15
A=1/5
Пусть x2=a (a>=0), тогда
a2+2a-3=0
D=4+12=16
a1=1
a2=-3 - посторонний корень
x2=1
x=1 и х=-1
Ответ: -1; 1
Решение во вложении--------------------------------