Question

mbn giải giúp mk bài nèy:

abcd5=5.abcd

Tìm abcd
 

Answer 1

Ta có :
Gọi số cần tìm là : abcd
=> abcd5=5.1abcd
=> a.10000+b.1000+c.100+d.10+5=5.(10000+a.1000+b.100+ c.10+d.1)
=> a.10000+b.1000+c.100+d.10+5=50000+a.5000+b.500+c.5 0+d.5
=> a.5000+b.500+c.50+d.5+5=50000
=> 5.(a.1000+b.100+c.10+d+1)=50000
=> a.1000+b.100+c.10+d+1=50000:5
=> a.1000+b.100+c.10+d+1=10000
=> a.1000+b.100+c.10+d+1=10000
=> abcd+1=10000
=> abcd=10000-1
=> abcd=9999
Vậy => abcd=9999

Answer 2

abcd5 = 5.abcd

abcd . 10 + 5 = 50000 + abcd

Cùng bớt 2 vế đi abcd + 5 ta được:

abcd . 9 = 49995

=> abcd = 49995 : 9

=> abcd = 5555

Answer 3

Hồ Thu Giang sai 

ko tìm dc số này       

Answer 4

 

abcd5=5.abcd

10000a+1000b+100c+10d+5=5.(1000a+100b+10c+d)

10000a+1000b+100c+10d+5=5000a+500b+50c+5d

10000a+1000b+100c+10d+5-5000a-500b-50c-5d=0

(10000a-5000a)+(1000b-500b)+(100c-50c)+(10d-5d)+5=0

5000a+500b+50c+5d+5=0

5.abcd+5=0

5.abcd=-5

abcd=-1(vô lí)