<span>2x-6y=10 у=(2х-10)/6 у=(х-5)/3
5x-4y=1, у=(5х-1)/4
</span>(х-5)/3= (5х-1)/4 домножим обе части на 12
4*(х-5)=3*(5х-1)
4х-20=15х-3
11х=-17
х= -17/11
у=(х-5)/3=(-1 6/11- 5)/3 = -6 6/11 :3 = - 72/33=-2 6/33
(-17/11 ;-72/33)
2cos37cos23-sin76=2*(1/2)*(cos(37-23)+cos(37+23))-sin76=
=cos14+cos60-sin76=cos14-sin76+1/2=cos14-sin(90-14)+1/2=cos14-cos14+1/2=1/2
3(2х-4)=2(х+3)
6х-18=2х+6
6х-2х=6+18
4х=24
х=6