cos x >1/2
Умножаем на 2.
2cosx>1
Возводим в квадрат левую и правую части.
4cos^2x>1
Действительных X нет.
(5^4*5^5)/5^7=5^9/5^7=5^2=25
<span> =
16+log</span>√6 <span>3 *(</span>2+log3 4)=
16+log3 <span>√6 </span>*(2+log3 <span>4)=
</span>16+2*log3 <span>√6+</span>log3 <span>√6 * </span>log3<span> 4=
</span><span>16+ 2*(log3 </span>√3 + log3 √2)+ (log3 √3 +log3 √2)* log3 <span>4=
</span><span>16+2*(1/2 + </span>log3 √2) + (1/2+log3 √2)* log3 4=
17+ log3 √2 + 1/2*log3 4 + log3 √2 * log3 4=
17+ log3 √2 + 2*log3 √2 + 4*log3 √2*log3 √2=
17+3*log3 √2+4(log3 √2)^2<span>
</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