2(3/2-x)-1/3=7x–1/4 1/5(-3/5–10)+5x=x–2/3

0 bình luận về “2(3/2-x)-1/3=7x–1/4 1/5(-3/5–10)+5x=x–2/3”

1. Đáp án: `x = 35/108`

                `x = 109/300 `

   Giải thích các bước giải:

   * ` 2( 3/2 – x ) – 1/3 = 7x – 1/4 ` *

   `⇒ ( 2 . 3/2 – 2x ) – 1/3 = 7x – 1/4 `

   `⇒ ( 3 – 2x ) – 1/3 = 7x – 1/4 `

   `⇒ 3 – 2x – 1/3 = 7x – 1/4  ⇒  ( 3 -1/3 ) – 2 = 7x – 1/4 `

   `⇒ 8/3 – 2x = 7x – 1/4  ` 

   `⇒ ( 7x – 1/4 ) –  8/3 + 2x  = 0` ( áp dụng quy tắc chuyển vế ) 

   `⇒ ( 7x + 2x ) + ( -1/4 – 8/3 ) = 0 `

   `⇒ 9x + (-35/12 )= 0`

   `⇒ 9x = 35/12  `

   `⇒ x =  35/12  : 9 = 35/108 `

   * `1/5 .( -3/5 – 10) + 5x = x – 2/3` *

   `⇒ [ 1/5 . ( -3/5 ) – 1/5 . 10 ] + 5x = x – 2/3 `

   `⇒ ( -3/25 – 2 ) + 5x = x – 2/3 `

   `⇒ -53/25 + 5x = x – 2/3 `

   `⇒ ( -53/25 + 5x ) + 2/3 = x `

   `⇒ ( -53/25 + 2/3 ) + 5x = x`

   `⇒ -109/75 + 5x = x `

   `⇒ -109/75 + 5x – x = 0 `

   `⇒ -109/75 + 4x = 0 `

   `⇒ 109/75 = 4x `

   `⇒ x = 109/75 : 4 = 109/300`

   Bình luận

2. Đáp án:

   `a,`

   `2 (3/2 – x) – 1/3 = 7x – 1/4`

   `-> 3 – 2x – 1/3 = 7x – 1/4`

   `-> 8/3 – 2x = 7x – 1/4`

   `-> 8/3 – 2x – 7x + 1/4 = 0`

   `-> 35/12 – 9x = 0`

   `-> 9x = 35/12`

   `-> x = 35/12 ÷ 9`

   `-> x = 35/108`

   Vậy `x = 35/108`

   `b,`

   `1/5 (-3/5 – 10) + 5x = x – 2/3`

   `-> (-3)/25 – 2 + 5x = x – 2/3`

   `-> (-53)/25 + 5x = x – 2/3`

   `-> (-53)/25 + 5x – x + 2/3 = 0`

   `-> (-109)/75 + 4x = 0`

   `-> 4x = 109/75`

   `-> x = 109/75 ÷ 4`

   `-> x =109/300`

   Vậy `x = 109/300`

    

   Bình luận