Toán Lớp 6: Tính hợp lí nhất
52 – (73 – 148) – 27
-15.(20-32) + 32.(20 – 15)
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Toán Lớp 6: Tính hợp lí nhất
52 – (73 – 148) – 27
-15.(20-32) + 32.(20 – 15)
Comments ( 2 )
$\textit{1.}$
$\textit{a) 52 – (73 – 148) – 27}$
$\textit{= 52 + 73 + 148 – 27}$
$\textit{= (52 + 148) – (73 + 27)}$
$\textit{= 200 – 100}$
$\textit{= 100}$
$\textit{b) -15. (20 – 32) + 32. (20 – 15)}$
$\textit{= -15. 20 – (-15). 32 + 32. 20 – 32. (-15)}$
$\textit{= -15. 20 + 15. (-32) + 32. 20 – 32. (-15)}$
$\textit{= [-15. (-32) + 32. (-15)] + [(- 15). 20 + 32. 20]}$
$\textit{= 0 + [(-15) + 32]. 20}$
$\textit{= 0 + 17. 20}$
$\textit{= 17. 20} $
$\textit{= 340}$