1-2cos^2(75)=-cos150=-cos(90+60)=sin60=√3/2
2.3*(|cosx|-1)*sin^2x/√sinx=-6sin^2x/2*sin^2x/√sinx=-6sinx*sin^2x/2*√sinx
cosx>=0 cosx-1=cos^2x/2-sin^2x/2-cos^2x/2-sin^2x/2=-2sin^2x/2
cosx<= -cosx-1=-2cos^2x/2
3*(|cosx|-1)*sin^2x/√sinx=-6sin^2x/2*sin^2x/√sinx=-6sinxcos^2x/2√sinx
2x+13y+10=0 |*6
6x-2y-11=0 |*-2
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12x+78y+60=0 x=2x+13*(-1)+10=0
-12x+4y+22=0 x=2x-13+10=0
82y+82=0 2x-3=0
82y=-82 2x=3
y=-1 x=3:2 x=1.5
Как-то так
<span>lg log_5 log_5 (x) = 0
</span>log_5 log_5 (x) = 10^0
log_5 log_5 (x) = 1
log_5 (x) = 5^1
x = 5^5
x = 3125
Метод сложения
7х+5х-у+у=10+2
12х=12
х=1
у=2-5х=2-5×1=-3
(1;-3)