17,58×43+57×17,58 43,57×2,6x(630-315×2) 45×16-17 phần 45x 15+28 Tìm x X/2+3/4=6/7 33,3:(x-3,5)+45,7=799 (X-1)+(X-2)+(X-3)+(X-4)=30

0 bình luận về “17,58×43+57×17,58 43,57×2,6x(630-315×2) 45×16-17 phần 45x 15+28 Tìm x X/2+3/4=6/7 33,3:(x-3,5)+45,7=799 (X-1)+(X-2)+(X-3)+(X-4)=30”

1. Câu 1:

   $\text{a) 17,58 × 43 + 57 × 17,58}$

   $\text{= 17,58 × (43 + 57)}$

   $\text{= 17,58 × 100}$
   $\text{= 1758}$

   $\text{b) 43,57 × 2,6 × (630 – 315 × 2)}$

   $\text{= 43,57 × 2,6 × 0}$

   $\text{= 0}$
   c) $\dfrac{45 × 16 – 17}{45 × 15 + 28}$ 

   $=\dfrac{45 × 15 + 45 – 17}{45 × 15 + 28}$ 

   $\text{= 1}$

   Câu 2: 

   a) $\dfrac{x}{2}$ + $\dfrac{3}{4}=$ $\dfrac{6}{7}$

   $\dfrac{x}{2}=$ $\dfrac{6}{7}-$ $\dfrac{3}{4}$

   $\dfrac{x}{2}=$ $\dfrac{3}{28}$ 

   $\text{x=}$ $\dfrac{3}{28}$  $\text{× 2}$

   $\text{x=}$ $\dfrac{3}{14}$ 

   b)$\text{33,3 : (x – 3,5)+ 45,7 = 799}$

   $\text{33,3 : (x – 3,5) = 799 – 45,7}$

   $\text{33,3 : (x – 3,5) = 753,3}$

   $\text{x – 3,5 = 33,3 : 753,3}$

   $\text{x – 3,5 =}$ $\dfrac{37}{837}$ 

   $\text{x =}$ $\dfrac{37}{837}$  $\text{+ 3,5}$

   $\text{x =}$ $\dfrac{5933}{1674}$ 

   c) $\text{(x – 1) + (x – 2) + (x – 3) + (x – 4) = 30}$
   $\text{x – 1 + x – 2 + x – 3 + x – 4 = 30}$

   $\text{4x – 10 = 30}$

   $\text{4x = 30 + 10}$
   $\text{4x = 40}$

   $\text{x = 40 : 4}$

   $\text{x = 10}$ 

   Trả lời

2. $1) 17,58×43+57×17,58$

   $⇒17,58×(43+57)$

   $⇒17,58×100$

   $⇒1758$

   $2) 43,57×2,6×(630-315×2)$

   $⇒43,57×2,6×0$

   $⇒0$

   $\text{3) $\dfrac{45×16-17}{45×15+28}$}$

   $\text{⇒$\dfrac{45×15+45-17}{45×15+28}$}$

   $\text{⇒$\dfrac{45×15+28}{45×15+28}$}$

   $⇒1$

   $\text{4) $\dfrac{x}{2}$+ $\dfrac{3}{4}$= $\dfrac{6}{7}$}$

   $\text{⇒$\dfrac{x}{2}$= $\dfrac{3}{28}$}$ 

   $⇒x×28=6$

   $\text{⇒x=$\dfrac{3}{14}$}$ 

   $5) 33,3÷(x-3,5)+45,7=799$

   $⇒33,3÷(x-3,5)=753,3$

   $⇒x-3,5=33,3÷753,3$

   $\text{⇒x-3,5=$\dfrac{37}{837}$}$

   $\text{⇒x=$\dfrac{37}{837}$+3,5}$

   $\text{⇒x= $\dfrac{5933}{1674}$}$ 

   $6) (x-1)+(x-2)+(x-3)+(x-4)=30$

   $⇒x-1+x-2+x-3+x-4=30$

   $⇒4x-10=30$

   $⇒4x=40$

   $⇒x=10$

    

   Trả lời