sin(3x-π )=√3/2. -sin(π-3x)=√3/2. - sin3x=√3/2. sin3x=-√3/2
3x=(-1)^n arcsin(-√3/2)+πn.n∈Z
3x=(-1)^(n+1)π/3 +πn
x= (-1)^(n+1) π/9 +πn/3. n∈Z
1) (4-3х)(4+х²)=4·4+4х²-3х·4-3х·х²=16+4х²-12х-3х³.
2) (3ху+у²)(х²+3ху)=3х³у+9х²у²+х²у²+3ху³=3х³у+10х²у²+3ху³.
3) (х³+4х)(2-х-4х)=(х³+4х)(2-5х)=2х³-5х⁴+8х-20х².
Х³-у³=<span> (х-у)(х²+ху+у²),
</span>если х-у=4, ху=14, то разность х³-у³=4·(х²+у²+14)
(х-у)²=4²=16,
ху=14,
<span>х²-2ху+у²=16
</span>
<span>х²+у²-28=16
</span>
<span>х²+у²=16+28
</span>
<span>х²+у²=44
</span>
х³-у³=4·(х²+у²+14)=4·(44+14)=4·58=232
5(x²+x-1)=26
5x²+5x-31=0
D=25+775=800>0
x1*x2=-31/5=-6,2
-5х²+8х -3=0
5х -8х+3=0
D/4=4²-5*3=1
х1=(4+1)/5=1
х2=(4-1)/5=3/5=0,6