Question

[Tran Tuan Phi]

1. Cho tam giac ABC co dien tich 180cm².Tren canh AB lay diem D sao cho AD=8.Tren BC lay E sao cho BE=1/3 BC.Biet dien tich tam giac BDE la 12cm².Tinh AB
2. Tim X

a)1/5*7+1/7*9+1/9*11+...+2005*2011+1/X=1/5*0,5

b)1-(11 1/2[hon so]+X-10,1)/8 2/5[hon so]=0

c)1-(5 2/9[hon so]+X7 7/18[hon so])/2 1/6[hon so]=0

Answer 1

[Nguyễn Quang khánh]

ban oi bai nay lam kieu j giup minh voi