cho a/b=c/d chung minh a-b/a+b=c-d/c+d
Cho a/b = b/c = c/d . CHung minh (a+b+c / b+c+d ) ^3 = a/d
\(\frac{a}{b}=\frac{b}{c}=\frac{c}{d}\)
=> \(\frac{a}{b}=\frac{b}{c}=\frac{c}{d}=\frac{a+b+c}{b+c+d}\)
=> \(\left(\frac{a+b+c}{b+c+d}\right)^3=\frac{a}{b}.\frac{b}{c}.\frac{c}{d}=\frac{a}{d}\)
=> ĐPCM
cho a/b=c/d chung minh a-b/a+b=c-d/c+d
\(\frac{a-b}{a+b}=\frac{\frac{a}{b}-1}{\frac{a}{b}+1}=\frac{\frac{c}{d}-1}{\frac{c}{d}+1}=\frac{\frac{c-d}{d}}{\frac{c+d}{d}}=\frac{c-d}{c+d}.\)
Vậy: \(\frac{a-b}{a+b}=\frac{c-d}{c+d}\)
\(\frac{a}{b}=\frac{c}{d}\Rightarrow\)\(\frac{a}{c}=\frac{b}{d}=\frac{a+b}{c+d}=\frac{a-b}{c-d}\)
\(\frac{a+b}{c+d}=\frac{a-b}{c-d}\Rightarrow\frac{a+b}{a-b}=\frac{c+d}{c-d}\)
cho a/b=b/c=c/d. chung minh(a+b+c/b+c+d)mu 3=a/d
Áp dụng t/c dãy tỉ số bằng nhau , ta có :
a/b = b/c = c/d = (a + b + c)/(b + c + d).
Suy ra : (a/b)^3 = (a+b+c/b+c+d)^3
Vậy (a+b+c/B+c+d)^3 = (a/b)^3 = (a/b).(a/b).a/b) = (a/b).(b/c).(c/d) = a/d (do rút gọn)
cho a/b = c/d chung minh
1 a . ( b - d ) = ( a - c ) . b
2 ( a + c ) . d = c . ( b + d )
Khi đó a(b - d) = (a - c)b
= ab - ad = ab - bc
=> ad = bc
=> \(\frac{a}{b}=\frac{c}{d}\)(đúng với giả thiết)
=> a(b - d) = (a - c)b (đpcm)
2) (a + c).d = c(b + d)
=> ad = cd = cb + cd
=> ad = cb
=> \(\frac{a}{b}=\frac{c}{d}\)(đúng với giả thiết)
=> (a + c)d = c(b + d) (đpcm)
cho a/b=b/c=c/d chung minh rằng a^3+c^3-b^3/c^3+b^3-d^3=a/d
biet (a+b+c+d).(a-b-c+d)=(a-b+c-d).(a+b-c-d) chung minh a/c=b/d
cho a/b=b/c=c/d=d/a trong đó a+b+c+d khác 0 chung minh rang a^20
cho a^2+b^2+(a-b)^2=c^2+d^2+(c-d)^2.chung minh a^4+b^4+(a-b)^4=c^4+d^4+(c-d)^4
Cho a/b = b/c = c/d (b,c,d # 0). Chung minh rang
a^3 + b^3 + c^3/ b^3+ c^3 + d^3 =a/b