6х+(х-3у)=6х+х-3у=7х-3у;///
12-(х-61)=12-х+61=-х+73;///
(12х-1)+(6х-4)=12х-1+6х-4=18х-5;///
(5а-2)-(4-3а)=5а-2-4+3а=8а-6;////
(1-9у)-(22у-4)-5=1-9у-22у+4-5=
-31у
1. 1.5х^2у^2
(х^2+2х)/2
(3(а-2))/а+3
<span>( (sin^2(</span>π<span>+ </span>α<span>)+sin^2(</span>π<span>/2 + </span>α<span>))= Sin</span>²α + Cos²α = 1<span>
cos(3</span>π<span>/2 + </span>α<span>) ) * сtg(3</span>π<span>/2 - </span>α<span>)= Sin</span>α * tgα= Sin²α/Сosα
Ответ: Cosα/Sin²α
1
{x+1≠0⇒x≠-1
{x²+4x-5<0⇒(x+5)(x-1)<0⇒-5<x<1
x∈(-5;-1) U (-1;1)
2
{x-y=3
{x²+y²=29
x=3+y
9+6y+y²+y²-29=0
2y²+6y-20=0
y²+3y-10=0
y1+y2=-3 Y y1*y2=-10
y1=-5⇒x1=-5+3=-2
y2=2⇒x2=2+3=5
(-2;-5);(5;2)