3^-7 *3^5= 3^-7+5=3^-2=1/9
(2/3)^7:(2/3)^10=27/8=3,375
3^-6*(3^-3)^-3= 3^-6*3^9=3^3=27
(1 1/6)^-2= (7/6)^-2=(6/7)^2=36/49
<span>Sin^2x +Sin x cos x-2 cos^2 x=0; / cos^2 x </span>≠ 0;
<span>tg^2 x + tg x - 2 = 0;
D = 1 + 8 = 9 = 3^2;
tg x = (- 1 + 3) / 2= 1;
tg x = pi/4 + pi*k ; k-Z.
tg x = ( - 1 - 3) / 2= - 2;
x = - arctg2 + pi*k; k-Z
</span>
Sn=((2*a1+d(n-1))*n)/2
S5=(2*3+(4*d))*5)/2=((6+4d)*5)/2
отсюда - d=(((2*S5)/5)-6)/4=(((2*65)/5)-6)/4=(26-6)/4=5
ответ: d=5