DE THI HSG LOP 6 HUYEN DIEN BAN day!!!!

bai 1

1)tinh tong\(\frac{3}{10}+\frac{3}{40}+\frac{3}{88}+\frac{3}{154}+\frac{3}{238}+\frac{3}{340}\) bang cach hop ly nhat(khong duoc quy dong truc tiep)

2)cho tap hop A={9,11,13,15,17,19,...}.Hay viet lai tap hop A bang cach chi ra tinh chat dac trung cho cac phan tu cua tap hop A

BAI2

1)cho A=2016²⁰¹⁷-2016²⁰¹⁶

B=2016²⁰¹⁸-2016^2017.Hay so sanh A va B

2)cho abc chia het cho 7 chung minh rang 2a+3b+c chia het cho 7

bai3

1)tim phan so nho nhat \(\frac{x}{y}\) sao cho khi chia phan so \(\frac{x}{y}\) chocac phan so \(\frac{35}{153};\frac{28}{425}\) ta duoc cac so tu nhien

2)mot nguoi ban xi mang (tinh bang bao) 3 lan:lan thu nhat ban \(\frac{5}{7}\) so bao xi mang trong kho lan thu hai ban \(\frac{3}{11}\) so bao xi mang con lai va lan thu 3 ban \(\frac{3}{5}\) so bao xi mang con lai cua 2 lan dau .luc nay so bao xi mang con lai trong kho la 256 bao.Hoikho xi mang co bao nhieu bao  va so bao xi mang moi lan ban la bao nhieu???

bai 4:cho 2 goc AOB va goc BOC la 2 goc ke bu.biet so do cua goc BOC bang 8 lan so do cua goc AOB

1)Tinh so do 2 goc AOB VA BOC

2)ve tham n tia phan biet goc tai O nam giua hai tia OC va OB.Ve them n+2 tia phan biet goc tai O nam giua hai tia OA va OB.Tinh so goc co trong hinh tren??????????????????????