3,8a+7,7+1,7b+2,5a+11,2+4,6b=
=(3,8a+ 2,5a)+(1,7b+4,6b)+(7,7+11,2)=
=6,3а+6,3в+18,9=
=6,3*(а+в+3)=
=6,3*10= 63
Раскроем скобки:
Cosα - Cosα + Cosα/4Sin²α = 1/4*Сtgα * Cosecα
6.11 б)
log3 (log2 x)=1
log3 (log2 x)=log3 3
log2x=3
log2 x=log2 8
x=8
<span>6.12 б
</span>log81 x+log9 x+log3 x=7
<span>Log3 x/log3 81 + log3 x/log3 9 + log3 x = 7 </span>
<span>log3 x/4 + log3 x/2 + log3 x = 7
</span>log (3)x + 2*log(3)x + 4*log(3)x = 28
<span>7 log(3)x = 28 </span>
<span>divide by 7 </span>
<span>log(3)x = 4 </span>
<span>3^4 = x </span>
<span>x= 81
</span>
<span>6.13 б
</span>log3 x+2log9 x+3log 27x+4log81x=8
<span>log[3]x+log[9]x^(2)+log[27]x^(3)+log[81]x^(4)=8
log[3]x+log[3^2]x^(2)+log[3^3]x^(3)+log[3^4]x^(4)=8
log[3]x+(2/2)log[3]x+(3/3)log[3]x+(4/4)log[3]x = 8
</span><span>log[3]x + log[3]x + log[3]x+</span><span>log[3]x</span><span> = 8
4 log[3]x = 8
log[3]x = 2
x = 3^2
x = 9 </span>
1)19*80=1520 - без скидки
2)1520:100*10=152- скидка
3)1520-152= 1368- заплатит за все покупки