Đáp án:
Giải thích các bước giải:
$a) x - 9178 = 121 × 5$
$⇒ x - 9178 = 605$
$⇒ x = 605 + 9178$
$⇒ x = 9783$
$b) ( x + 1997) + 2003 = 5432$
$⇒ x + 1997 = 5432 - 2003$
$⇒ x + 1997 = 3429$
$⇒ x = 3429 - 1997$
$⇒ x = 1432$
$c) 125 - ( 25 + x ) = 7 × 9$
$⇒ 125 - ( 25 + x ) = 63$
$⇒ 25 + x = 125 - 63$
$⇒ 25 + x = 62$
$⇒ x = 62 - 25$
$⇒ x = 37$
$d) 329 - ( 129 + x ) = 14 × 7$
$⇒ 329 - ( 129 + x ) = 98$
$⇒ 129 + x = 329 - 98 $
$⇒ 129 + x =231$
$⇒ x = 231 - 129$
$⇒ x = 102$
$ e) (x + 1) + (x + 2) + (x + 3) + .......+ ( x + 2020 ) = 2045250$
$⇒ x + 1 + x + 2 + x + 3 + ...... + x + 2020 = 2045250$
$⇒ ( x + x + x + .... + x ) + ( 1 + 2 + 3 + ..... + 2020 ) = 2045250$
$⇒ 2020 × x + 1010 × 2021 = 2045250$
$⇒ 2020 × x + 2041210 = 2045250$
$⇒ 2020 × x = 2045250 - 2041210$
$⇒ 2020 × x = 4040$
$⇒ x = 4040 : 2020 $
$⇒ x = 2$
