<span>-3х+7у+13х-7у-3=(-3х+13х)+(7у-7у)+3=10х+3</span>
2cos 165+75/2*cos165-75/2=2cos120*cos45=2 * (-1/2) * √2/2=-√2/2
Получаем а в -12 степени делящаяся на а в 15 степени.
Получили а в -27 степени или 1 поделить на а в 27 степени
2.10 b) a² -ac +bc -ab =a(a -c) -b(a -c) =(a -c)(a -b)
(a+2b)/3(a -b) -(3c -a)/2(a-c) +(a² -bc)/(a -c)(a -b) =
=(2(a-c)(a+2b) -3(a-b)(3c-a) +6(a²-bc)) /6(a-c)(a-b) =
=(2(a²+2ab-ac-2bc) -3(3ac-a² -3bc+ab) +6a² -6bc) /6(a -c)(a -b) =
=(2a²+4ab -2ac-4bc -9ac +3a² +9bc -3ab +6a² -6bc) /6(a -c)(a -b) =
=(11a² +ab -11ac -bc) /6(a -c)(a -b) =
=11a(a -c) +b(a -c)) /6(a -c)(a -b) =
=(a -c)(11a +b) /6(a -c)(a -b) =
=(11a +b) /6(a -b) =(11/6 -1) /6(1/6 +1) =
=(11-6)/6 : 6*7/6 =5/6 : 7 =5/6 *1/7 =5/42