a²+a-2a-2 -(a²-5a+3a-15) = a²+a-2a-2-a²+5a-3a+15 =a-2a-2+5a-3a+15 =
= a+13
при a= -1/2, a+13= 13-1/2 =12
при
a²+a-2a-2 -(a²-5a+3a-15) = a²+a-2a-2-a²+5a-3a+15 =a-2a-2+5a-3a+15 =
= a+13
при a= -1/2, a+13= 13-1/2 =12