1) 1/2*1/6=1/12 ; 1/3*1/4=1/12. Ta có : 17/5+1/12*71/5-1/12*28/5=1/12*(17/5+71/5-28/5)=1/12*60/5=1/12*12=1 2)1/10+4/20+9/30+16/40+25/50 =1/10+2/10+3/10+4/10+5/10(rút gọn) =15/10=3/2 3)18/15*(2525/3636+1515/1818-2020/7272)=6/5*(25/36+5/6-5/18)(rút gọn)=6/5*25/36+6/5*5/6-6/5*5/18=5/6+1-1/3=9/6=3/2.
Xin lỗi tôi nhầm ở chỗ 17/5+1/12*71/5. Xin thông cảm và sửa lại thành 17/5*1/12+71/5*1/12-28/5*1/12 rồi điền đúng vào đó
sieu tat nhe !!!!!!!!!!
1) <=>17/12+71/20-28/60
<=>85/60+213/60-28/60
<=>270/60=9/2
2)<=>1/10+2/10+3/10+4/10+5/10+6/10+7/10+9/10+8/10
=1+2+3+4+5+6+7+8+9/10
=45/10=9/2
3)rut gon di ta co
=18/15.(25/36+15/18-20/72)
=18/15.(50/72+60/72-20/72)
=18/15.90/72
=1620/1080(bo cung duoc)
=3/2