Sinx^2+cosx^2=1
<span>cosx=√(1-9*11/100)=+√(0.01)=+0.1 т. к. cosx>0 при 0<x<90</span>
<span>7x-(x+3)=3(2x-1)
7х-х-3=6х-3
6х-3=6х-3
6х-6х=-3+3
0х=0
х-любое</span>
Х+у=-3 | 3
3х+3у= -9
(3х+3у)+(-3х+3у)=-18
6у=-18
у=- 18:6
у=-3
х+у=-3
х=3+(-3)
х=0
9x^2+64-48x>=64x^2+9-48x
-55x^2>=- 55
x^2<=1
x<=(+-1)
Ответ: [-1;1]