Ta chứng mih : a/b <a+c/b+d ,biet a/b <c/d
Theo đề bài ta có :a/b < c/d => ad<bc
=>ad+ab<bc+ab=>a(d+b)<b(c+a)=>a/b < a+c/b+d
Tương tự :a/b < c/d =>a+c / b+d<c/d
Vay :a/b < a+c / b+d <c/d
Cho hai so huu ti a/b va c/d (b>0, d>0). Chung to rang :
a, Neu a/b < c/d thi ad<cd
b, Neu ad<bc thi a/b < c/d
cac ban cho minh hoi
chung to rang neu a/b<c/d (b>0,d>0) thi a/b<a+c/b+d<c/d
Chon cau tra loi dung Neu a+b/b+c=c+d/d+a thi
a)a phai bang c
b)a=c hay a+b+c+d=0
c)a+b+c+d phai bang 0
d)a+b+c+d khac 0 neu a=c
a)Chung to rang neu a/b <c/d (b<0,d<0) thi a/b < a+c/d+b < c/d
b)Hay viet 3 so huu ti xen giua -1/3 va -1/4
chung to rang neu a/b<c/d (b,d>0) thi a/b < a+c/b+d < c/d
chun to ran neu \(\frac{a}{b}\)<\(\frac{c}{d}\)(b.0,d>0) thi \(\frac{a}{b}\)<\(\frac{a+c}{b+d}\)<\(\frac{c}{d}\)
cho a,b,c,d thuoc Z va 0<a<b<c<d chung minh rang neu a/bc/d thi a+d>b+c
Cho a;b;c thuoc Z b;d;c>0 .CMR:
Neu a>b thi a/b>a+c/b+c
Neu a<b thi a/b<a+c/b+c
cho so huu ti a/b va c/d voi b>0 chung to rang neu a/b > c/d thì a/b<a+c/b+d <c/d
