tìm x ∈ N , biết a, 321 + x = 2016 b, 48 – 3(x + 5 ) = 24 c, 1230 : 3(x – 20 ) = 10 d, x + 37= 50 e , 2. x – 3 = 11 f, (2 + x ) : 5 = 6

0 bình luận về “tìm x ∈ N , biết a, 321 + x = 2016 b, 48 – 3(x + 5 ) = 24 c, 1230 : 3(x – 20 ) = 10 d, x + 37= 50 e , 2. x – 3 = 11 f, (2 + x ) : 5 = 6”

1. a)

   `321+x=2016`

   `⇒x=1695`

   b)

   `48-3(x+5)=24`

   `⇒3(x+5)=24`

   `⇒x+5=8`

   `⇒x=3`

   c)

   `1230:3(x-20)=10`

   `⇒3(x-20)=123`

   `⇒x-20=41`

   `⇒x=61`

   d)

   `x+37=50`

   `⇒x=13`

   e)

   `2x-3=11`

   `⇒2x=14`

   `⇒x=7`

   f)

   `(2+x):5=6`

   `⇒2+x=30`

   `⇒x=28`

    

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2. a, 321 + x = 2016

   =>x=2016-321

   =>x=1695

   b, 48 – 3(x + 5 ) = 24

        => 3(x+5)=48-24

   =>3(x+5)=24

   =>x+5=8

   =>x=3

   c, 1230 : 3(x – 20 ) = 10

   =>3(x-20)= 1230:10

   =>3(x-20)= 123

   =>x-20=123:3

   =>x-20=41

   =>x=61

   d, x + 37= 50

   x=50-37

   x=13

   e , 2. x – 3 = 11

   2x=11+3

   2x=14

   x=14:2=7

   f, (2 + x ) : 5 = 6

   2+x=5.6

   2+x=30

   x=30-2

   x=28

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