а) x^2+2x
прибавь один: x^2+2x+1=(x+1)^2
б)<span> a²+4ab</span>
<span>
</span>
<span>прибавь 4b^2: <span> a²+4ab+4b^2=(a+2b)^2</span></span>
<span><span>
</span></span>
<span><span>в) <span>m² +1</span></span></span>
<span><span><span>
</span></span></span>
<span><span><span>прибавь 2m: <span>m² +1 +2m=(m+1)^2</span></span></span></span>
1. а) x15
б) x10
в) х28
3. 6х-4-12х+9=2-4х
6х-12х+4х=4-9+2
-6х+4х=-5+2
-2х=-3
х=2/3
Cos<span>^2 <span>α</span>+Ctg^<span>2 <span>α</span>-1/Sin<span>^2 <span>α = Cos^2 α+Ctg^2 α-1-Ctg^2 α = Cos^2 α-1= Cos^2 α-Sin^2 α-Cos^2 α = -Sin^2 α
Вроде так. </span></span></span></span>