Question

Tính hợp lí: 
(-8) . (12+14) + 12 . (8-14)

 

Answer 1

\((-8)\cdot(12+14)+12\cdot(8-14)\\=-8\cdot12+(-8)\cdot14+12\cdot8+12\cdot(-14)\\=(-8\cdot12+12\cdot8)+8\cdot(-14)+12\cdot(-14)\\=-14\cdot(8+12)\\=-14\cdot20\\=-280\)

Answer 2

\(\left(-8\right).\left(12+14\right)+12.\left(8-14\right)\\ =-8.12-8.14+12.8-12.14\\ =\left(12.8-8.12\right)-14.\left(8+12\right)\\ =0-14.20=-280\)

Answer 3

(−8)⋅(12+14)+12⋅(8−14)=−8⋅12+(−8)⋅14+12⋅8+12⋅(−14)=(−8⋅12+12⋅8)+8⋅(−14)+12⋅(−14)=−14⋅(8+12)=−14⋅20=−280