a)9/17-3/5+8/17-1/5 b)1/5+3 2/7-7 1/5 +4 5/7 c) 6- 5 1/3 +3 1/3 d)7/12 – 3 1/5+1 5/12+ 4 1/5 đ)3/4- (-1/2)-5/6 e)-5+2 2/5 -(-3 3/

0 bình luận về “a)9/17-3/5+8/17-1/5 b)1/5+3 2/7-7 1/5 +4 5/7 c) 6- 5 1/3 +3 1/3 d)7/12 – 3 1/5+1 5/12+ 4 1/5 đ)3/4- (-1/2)-5/6 e)-5+2 2/5 -(-3 3/”

1. Đáp án:

    $a) \dfrac{1}{5}\\
   b)1\\
   c)4\\
   d)3\\
   đ)
   \dfrac{5}{12}\\
   e)
   1$

   Giải thích các bước giải:

    $a) \dfrac{9}{17}-\dfrac{3}{5}+\dfrac{8}{17}-\dfrac{1}{5}\\
   =\left (\dfrac{9}{17}+\dfrac{8}{17}  \right )+\left (-\dfrac{3}{5}-\dfrac{1}{5}  \right )\\
   =\dfrac{17}{17}+\dfrac{-4}{5}\\
   =\dfrac{5}{5}-\dfrac{4}{5}\\
   =\dfrac{1}{5}\\
   b) \dfrac{1}{5}+3\dfrac{2}{7}-7\dfrac{1}{5}+4\dfrac{5}{7}\\
   =\left ( \dfrac{1}{5}-7\dfrac{1}{5} \right )+\left ( 3\dfrac{2}{7}+4\dfrac{5}{7} \right )\\
   =\left ( -7+\dfrac{1}{5}-\dfrac{1}{5} \right )+\left ( 3+4+\dfrac{2}{7}+\dfrac{5}{7} \right )\\
   =-7+7+1\\
   =1\\
   c) 6-5\dfrac{1}{3}+3\dfrac{1}{3}\\
   =6+\left ( -5+3-\dfrac{1}{3}+\dfrac{1}{3} \right )\\
   =6-2\\
   =4\\
   d) \dfrac{7}{12}-3\dfrac{1}{5}+1\dfrac{5}{12}+4\dfrac{1}{5}\\
   =\left (\dfrac{7}{12}+1\dfrac{5}{12}  \right )+\left ( -3\dfrac{1}{5}+4\dfrac{1}{5} \right )\\
   =\left ( 1+\dfrac{7}{12}+\dfrac{5}{12} \right )+\left ( -3+4+\dfrac{-1}{5}+\dfrac{1}{5} \right )\\
   =(1+\dfrac{12}{12})+1\\
   =1+1+1\\
   =3\\
   đ)
   \dfrac{3}{4}-\dfrac{-1}{2}-\dfrac{5}{6}\\
   =\dfrac{3}{4}+\dfrac{1}{2}-\dfrac{5}{6}\\
   =\dfrac{9}{12}+\dfrac{6}{12}-\dfrac{10}{12}\\
   =\dfrac{5}{12}\\
   e)
   -5+2\dfrac{2}{5}-\left ( -3\dfrac{3}{5} \right )\\
   =-5+2\dfrac{2}{5}+3\dfrac{3}{5}\\
   =-5+2+3+\dfrac{2}{5}+\dfrac{3}{5}\\
   =-5+5+\dfrac{5}{5}\\
   =1$

   Trả lời