Bài 1:Tính hợp lý a) A= $\frac {-5}{11}$ + 75% -1$\frac{1}{2}$ -$\frac{1}{4}$ +$\frac{6}{-11}$ b)B= $\frac{19-19.5}{19.2-76}$ c)C= $\frac{-7}{11}$.

0 bình luận về “Bài 1:Tính hợp lý a) A= $\frac {-5}{11}$ + 75% -1$\frac{1}{2}$ -$\frac{1}{4}$ +$\frac{6}{-11}$ b)B= $\frac{19-19.5}{19.2-76}$ c)C= $\frac{-7}{11}$.”

1. Đáp án:

   Bài 1

   a)$\frac{-3}{2}$

   b) 2

   c) $\frac{-1}{11}$ 

   d)$\frac{51}{8}$ 

   Bài 2

   a) $\frac{35}{12}$

   b) $\frac{5}{2}$

   c) $\frac{21}{16}$

   d) $\frac{-5}{21}$

   Giải thích các bước giải:

   Bài 1

   A = $\frac{-5}{11}$+ 75% -1 $\frac{1}{2}$ + $\frac{1}{4}$ + $\frac{6}{-11}$

   = ($\frac{-5}{11}$ + $\frac{-6}{11}$) +($\frac{3}{4}$+$\frac{1}{4}$) +$\frac{-3}{2}$

   =$\frac{-11}{11}$ +1 +$\frac{-3}{2}$

   = -1 +1 +$\frac{-3}{2}$

   = $\frac{-3}{2}$

   b) B = $\frac{19 -19.5}{19.2-76}$ 

   =$\frac{19 .1- 19. 5}{19.2-19.24}$ 

   =$\frac{19 .(1-5)}{19.(2-4)}$ 

   =$\frac{19 -(-4)}{19.(-2)}$ 

   = 2

   c)C= $\frac{-7}{11}$. $\frac{4}{13}$+ $\frac{7}{11}$. $\frac{-9}{13}$+ $\frac{6}{11}$ 

   =$\frac{-7}{11}$. ($\frac{4}{13}$+ $\frac{9}{13}$) $\frac{6}{11}$

   = $\frac{-7}{11}$ . 1 + $\frac{6}{11}$ 

   = $\frac{-1}{11}$ 

   d) D= 7 $\frac{5}{11}$ – (5$\frac{5}{8}$-4 $\frac{6}{11}$ )

   = 7 $\frac{5}{11}$ – 5$\frac{5}{8}$+4 $\frac{6}{11}$

   = (7$\frac{5}{11}$ +4$\frac{6}{11}$ ) – 5$\frac{5}{8}$

   = 12 – 5 – $\frac{5}{8}$ 

   = 7 – $\frac{5}{8}$ 

   = $\frac{51}{8}$ 

   Bài 2 Tìm x , biết

   a) $\frac{3}{7}$ x – $\frac{3}{4}$= $\frac{1}{2}$

   $\frac{3}{7}$ x = $\frac{1}{2}$ + $\frac{3}{4}$

   $\frac{3}{7}$ x = $\frac{5}{4}$ 

   x = $\frac{5}{4}$ : $\frac{3}{7}$

   x= $\frac{35}{12}$ 

   b) $\frac{7}{12}$- 2$\frac{1}{2}$ : x =$\frac{-5}{12}$

   $\frac{5}{2}$ : x = $\frac{7}{12}$ –  $\frac{-5}{12}$

   x =$\frac{5}{12}$  : 1

   x= $\frac{5}{2}$ 

   c) x : ($\frac{3}{8}$ – $\frac{3}{4}$ )= -3$\frac{1}{2}$

    x : $\frac{-3}{8}$ = $\frac{-7}{2}$

   x = $\frac{-7}{2}$ . $\frac{-3}{8}$

   = $\frac{21}{16}$ 

   d) (2x+ $\frac{3}{4}$ ) ( $\frac{5}{7}$ – 3x)= 0  

   2x +  $\frac{3}{4}$  = 0 hoặc $\frac{5}{7}$ – 3x = 0

   2x = $\frac{-3}{4}$

   x = $\frac{-3}{4}$ : 2 

   x = $\frac{-3}{8}$

   —————————-

   $\frac{5}{7}$ – 3x = 0

   3x = $\frac{-5}{7}$

   x= $\frac{-5}{7}$ : 3

   x = $\frac{-5}{21}$

   Chúc bạn học tốt

   @Lichaeng

    

   Trả lời