<span>(1)а*b=b*a.<span>(2)a*(b+c)=(a+b)*c.<span>(3) (a*b)*c =(a*c)*b.<span>(4)a(b-c)=a*b-a*c.</span></span></span></span>
1+2+3=6
<span>((1/sin^2x)-(1/4sin^2x/2))</span>
10.5-(2х-3)=4.2
10.5-2х+3=4.2
-2х=4.2-10.5-3
-2х=-9.3
х=-9.3:(-2)
х=4.65
ОТВЕТ: 4.65