<span>cos2x - cos^2 x = -0.25
</span>cos^2 x - sin^2 x - cos^2 x =-0,25
- sin^2 x =- 0.25
sin x =0.5
x= 30 град
Х+6=5+4х
х-4х=5-6
-3х=-1
х=-1/(-3)
х=1/3
13-3(х+1)=4-5х
13-3х-3=4-5х
-3х+5х=4-13+3
2х=-8
х=-8/2
х=-4
<span>
0,2(3х-5)-0,3(х-14)=-0,7
</span>0.6х-1-0.3х+4.2=-0.7
0.3х=-0.7+1-4.2
0.3х=-3.9
х=-3.9/0.3
х=-13
<span>
-6=-2-(4+9х)</span>
-6=-2-4-9х
-9х=-2-4+6
-9х=0
х=-9
<span>1,2(5-4х)=-6(0,8х+1)
</span>6-4.8х=-4.8х-6
-4.8х+4.8х=-6-6
х=-12
B-a=x ⇒ a=b-x ⇒ a<b<c a b c
c-b=x ⇒ c=b+x --o-----------o-----------o
b²-ac=64 8 8
b²-(b-x)(b+x)=64 8+8=16
b²-(b²-x²)=64 Ответ:16
x²=64
x=8 ⇒ b-a=8
Через точки А (3=3*1*1), С(12=3*2*2), F(27=3*(-3)*(-3))
<span>1)
2x</span>²<span>+ 24xy +72y</span>² = 2 ·(х²+12ху+36у²) = 2·(х+6у)² = 2·(х+6у)(х+6у)
<span>2)
-8a</span>⁵<span> +8а</span>³<span> - 2а = -2а</span>·(4а⁴-4a²+1) = -2a·(2a²-1)² = -2a·(2a²-1)(2a²-1)
<span>3)
5a</span>³<span> - 40b</span>⁶ = 5a³ ·(1-8b³) = 5a³ ·(1³ - (2b)³) = 5a³·(1-2b)(1+2b+4b²)
<span>4)
8а</span>³<span> -аb - a</span>²<span>b + а</span>² = a·(8a²-b-ab+a)