Question

2а(3а-5)-4а(4а-5)=?
а=-0,2
Помогите пожалуйста!!!

Answer 1

$2a(3a-5)-4a(4a-5)=6a^2-10a-16a^2+20a=-10a^2-10a+20a=-10a^2+10a\\\\a=-0.2\\\\-10*(-0.2)^2+10*(-0.2)=-10*(-0.2)^2-10*0.2=-0.2*10(0.2+1)=\\\\=-0.2*10*1.2=-0.2*12=\boxed{-2.4}$