tính nhanh (-1907-2134)-(1907-1134) 199.(15-17)-199.(-17+5)

1) (-1907-2134)-(1907-1134)

= -1907-2134-1907+1134

= (-2134+1134)-( 1907+1907)

= -1000-3814

= -4814

2)199.(15-17)-199.(-17+5)

=  199.-2-199.-12

= 199( -2+12)

= 199.10

= 1990

Đáp án:

$\textit{(-1907 - 2134) - (1907 - 1134)}$

$\textit{⇒ -1907 - 2134 - 1907 + 1134}$

$\textit{⇒ (-2134 + 1134) - (1907 + 1907)}$

$\textit{⇒ -1000 - 3814}$

$\textit{⇒ -4814}$

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$\textit{199 . (15 - 17) - 199 . (-17 + 5)}$

$\textit{⇒ 199 . (-2) - 199 . (-12)}$

$\textit{⇒ 199 . [-2 - (-12)]}$

$\textit{⇒ 199 . 10}$

$\textit{⇒ 1990}$