2*(4-12a+9a²)-18a²+16a=8-24a<u>+18a²-18a²</u>+16a=8-8a=8*(1-a)=8*(1-(-0,2)=8*1,2=9,6
<span>Всего вариантов 6 * 6 = 36. </span>
<span>Из них 2: </span>
<span>3 = 1 + 2 и 3 = 2 + 1. </span>
<span>2/36 = 1/18.</span>
1. a1=7 a6=25
a6=7+d*5 7+5d=25 5d=18 d=18/5=3.6
a4=7+3d=4+3*3.6=14.8
2. a10=1.9 a16=6.1 a1,d?
a1+9d=1.9
a1+15d=6.1
15d-9d=6.1-1.9
6d=5.1 d=0.85 a1=1.9-9*0.85=1.9-7.65=-5.75
a)cos(6t+π/2)=-√3/2
-sin6t=-√3/2
sin6t=√3/2
[6t=π/3+2πk⇒t=π/18+πk/3
[6t=2π/3+2πk⇒t=π/9+πk/3
б)-2sinxcos2x/(1+cosx)=0
1+cosx≠0⇒cosx≠-1⇒x≠π+2πk-ОДЗ
sinx=0⇒x=πk+ОДЗ⇒x=2πk
cos2x=0⇒2x=π/2+πk⇒x=π/4+πk/2
в)
4sin²3x+4cos²3x-cos²3x-3sin²3x-4sin3xcos3x=0
sin²3x-4sin3xcos3x+3cos²3x=0/cos²3x
tg²3x-4tg3x+3=0
tg3x=a
a²-4a+3=0
{a1+a2=4
{a1*a2=3
a1=1⇒tg3x=1⇒3x=π/4+πk⇒x=π/12+πk/3
a2=3⇒tg3x=3⇒3x=arctg3+πk⇒x=1/3*arctg3+πk/3