Question

tính hợp lí

29. ( 19 - 13 ) - 19. ( 29 - 13 )

31. (-18)+31.(-81)-13

giúpp nha ><

Answer 1

\(29\cdot\left(19-13\right)-19\cdot\left(29-13\right)\\ =29\cdot19-29\cdot13-19\cdot29+19\cdot13\\ =\left(29\cdot19-19\cdot29\right)+\left(19\cdot13-29\cdot13\right)\\ =0+13\left(19-29\right)\\ =13\cdot\left(-10\right)\\ =-130\)

Answer 2

31.(-18)+31.(-81)-13

=31.(-18+(-81))-13

=31.(-99)-13

=-3069-13

=-3082