!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
3(а-2) -(а+4) = 3а - 6 - а - 4 = 2а - 10
При а = -1,5 2а - 10 = 2*(-1,5) - 10 = -3 - 10 = -13
Ответ. -13
<span>(2a+1)^2-(a-9)^2=(2a+1-a+9)(2a+1+a-9)= (a+10)(3a-8)</span>