Question

[Nguyen Duc Trung Thanh]

Cho hai phan so bang nhau a/b=c/d.Chung to rang:

a)a+b/b = c+d/b

b)a-b/b=c-d/d

c)a/a+b=c/c+d

d)a/a-b=c/c-d

Answer 1

[Em là Sky yêu dấu]

a) a/b=c/d =>ad=bc=>ad+bd=bc+bd=>d(c+d)=b(c+d)=>a+b/b=c+d/d

b)a/b=c/d=>ad=bc=>ad-bd=bc-bd=>(a-b)a=b(c-d)nên a-b/b=c-d/d

c)a/b=c/d=>cd=ad=>cb+ad=>cd+ac=ad+ac=>c(a+b)=a(c+d)nên dpcm

d)a/b=c/d=>ad=cd=>ad+ac=cb+ac=>ac-ad=cb-ac=>a(c-d)=c(b-a)nên dpcm

hihihihi

Answer 2

[Đỗ Thị Bách Hợp]

a) a/b=c/d =>ad=bc=>ad +bd=bc+bd=>d(c+d)=b(c+d)=>a+b/b=c+d/d