Question

4a^2+9b^2-(2a-3b)^2 при а=-15,1 b=1/2

Answer 1

4a²+9b²-(2a-3b)²=4a²+9b²-(4a²-12ab+9b²)=
=4a²+9b²-4a²+12ab-9b²=12ab

12ab=12.(-15).(1/2)=6.(-15)=-90