<span>4 (у+2)=-2
4y+8</span><span>=-2
4y</span><span>=-2-8
4y</span><span>=-10
y</span><span>=-10/4
y</span>=-5/2<span>=-2,5</span>
0,6*10000+4*(-1000)+70=6000-4000+70=2070
(3с+15)/(с^2-25)=(3*(с+5))/((с-5)*(с+5))=3/(c-5)
2sin^2x+5cosx-4=0
2-2cos^2x+5cosx-4=0, замена cosx=t
-2t^2+5t-2=0
t1=2; посторонний корень.
t2=1/2
cosx=1/2
<span>х=+-пи/3+2пиn</span>