Toán Lớp 6: bài 1 tìm x , biết
a] 123 – 5 . [ x : 2 ± 4 ] =38 b] x : 15 , x : 18
c] 25 : x d] 25 – [ x -1 ] ± 12 =5
Leave a reply
Register Now
Login
Lost Password
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Toán Lớp 6: bài 1 tìm x , biết
a] 123 – 5 . [ x : 2 ± 4 ] =38 b] x : 15 , x : 18
c] 25 : x d] 25 – [ x -1 ] ± 12 =5
Comments ( 1 )
5.(x:2+4)=123-38
5.(x:2+4)=85
x:2+4=85:5
x:2+4=17
x:2=17-4
x:2=13
x=13.2
x=26
b)xvdots15;xvdots18
=>x inBC(15;18)
Ta có :
15=3.5
18=2.3^2
=>BCN N(15;18)=2.3^2. 5=90
=>B(90)=BC(15;18)={0;90;180;270;360;…………..}
=>x={0;90;180;270;360;…………..}
c)25vdotsx
=>x in Ư(25)
=>x={1;5;25}
d)25 -(x -1)+ 12 =5
25-(x-1)=5-12
25-(x-1)=-7
x-1=25-(-7)
x-1=25+7
x-1=32
x=32+1
x=33