A)
2a^2 - B =
( 2×(-4))^2-1/2=
(-8)^2 -1/2=
64-1/2=63 1/2
B)
(2m-3n)^2=
(2×(-1)-(-5))^2=
(-2+5)^2=
3^2=9
C)
6m-14n-6m+30n+2m-2n=
2m+14n=
4×(-0,1)+14×(-4)=
-0,4+(-56)=-56,4
D)
3b^2+2b=
(3×(-4))^2+2×(-4)=
-12^2+(-8)=
144-8=136
E)
(2x+3y)(5-x)=
10x-2x^2+15y-3xy=
10×2-(2×2)^2+15×(-3)-3×2×(-3)=
20-16+(-45)-6×(-3)=
4-45+18=-23
