Сtg(270 +30)* sin (180+30)*cos(180*7-30)=-tg30 *(-sin30)*(-cos30)=-√3/3 * (-1/2)*(-√3/2)=
=-1/4
А) (6a+2b)^2 = 36a^2+16ab+4b^2
б) (<span>2x-5)^2= 4x^2- 14x+25
в) </span><span>(7a+2b)*(2b-7a)= 14ab-49a^2+4b^2-14ab= 4b^2-49a^2
г) </span><span>(2n^2+n)*(-2n^2+n)= -4n^4+ 2n^3- 2n^3+n^2= n^2-4n^4</span>
4^120 * 6^123 : 3 * 24^120 = 4^120 * 216^120 : 72^120 = 864^120 : 72^120 = 12^120