cho ti le thuc a^2+b^2/c^2+d^2 voi a b c d khac 0va c khong bang -d

cmr a/b=c/d hoac a/b=d/c

Cho a^2+b^2tat ca/c^2+d^2 =ab/cd

va a,b,c,d khac 0

cm a/b=c/d hoac a/b=d/c

voi a,b,c,d, la cac so duong thoa man a*b = c*d =1 chung minh bat dang thuc : ( a+b )*( c+d ) +4 >= 2*( a+b+c+d ) cac ban oi giup minh voi OK

Voi a,b,c la cac so duong  thoa man a*b =c*d =1 chung minh (a+b)(c+d) + 4>= 2(a+b+c+d)

voi a,b,c,d la cac so duong thoa man a*b = c*d = 1. Chung minh bat dang thuc ( a+b )*( c+d ) + 4 >= 2( a+b+c+d ) 

Cho duong tron(O) duong kinh AB,M la diem chinh giua cua 1 nua duong tron, C la diem bat ki tren nua duong tron kia CM cat AB tai D. ve day AE vuong goc voi CM tai F

a) chung minh rang tu giac ACEM la hinh thang can

b) ve CH vuong goc voi AB. Chung minh rang tia CM la tia phan giac cua goc HCO

c) chung minh rang CD nho hon hoac bang 1/2 AE

cho a/b<c/d, a, b, c, d la nhung so nguyen duong. hay so sanh a/b, c/d voi a-c/b-d

B1: cho a,b,c la cac so nguyen duong

CMR:neu a /b >hoac bang c/d thi a/b > hoac bang a+c/b+d > hoac bang c/d

B2: Tim PS nho nhat khac 0 sao cho khi chia no cho 14/9 ; cho 45/27 deu duoc thuong la cac so tu nhien 

B3:CMR: 1/2^2 + 1/4^2 + 1/6^2 +....+ 1/100^2 < 1/2

Ve tren cung mot hinh theo cach dien dat sau :

a)Ve 4 diem A ,B ,C D sao cho C nam giua A, B va 3 diem A, B D ko thang hang . Hay ve va ke ten duong thang (phan biet) di qua tung cap diem .

b) Ve diem E sao cho E va D nam khac phia doi voi A . Ve diem F sao cho C,E,F thang hang va F thuoc duong thang DB