cho 3 so a,b,c thoa man \(\frac{a}{3}\) = \(\frac{b}{8}=\frac{c}{5}\) va 2a+3b-c=50.tinh tong cua 3 so a,b,c bang
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cho cac so a,b,c va thoa man \(\frac{ab}{a+b}=\frac{1}{3},\frac{bc}{b+c}=\frac{1}{4},\frac{ca}{c+a}=\frac{1}{5}\)Tinh gia tri bieu thuc P=\(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}\)
Thêm đk \(a,b,c\ne0\)
Ta có: \(\frac{ab}{a+b}=\frac{1}{3}\Rightarrow\frac{a+b}{ab}=3\)
\(\frac{bc}{b+c}=\frac{1}{4}\Rightarrow\frac{bc}{b+c}=4\)
\(\frac{ca}{c+a}=\frac{1}{5}\Rightarrow\frac{c+a}{ca}=5\)
\(\Rightarrow\frac{a+b}{ab}+\frac{b+c}{bc}+\frac{c+a}{ca}=12\)
\(\Leftrightarrow\frac{1}{b}+\frac{1}{a}+\frac{1}{c}+\frac{1}{b}+\frac{1}{a}+\frac{1}{c}=12\)
\(\Leftrightarrow2\left(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}\right)=12\)
\(\Leftrightarrow\frac{1}{a}+\frac{1}{b}+\frac{1}{c}=6\)
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cau 1: Cho A frac{100^{2014}+2}{3}-frac{100^{2015}+17}{9}.tong cac cua so cua B-9ACau 2: So sanh Afrac{1}{1.2}+frac{1}{2.3}+frac{1}{3.4}+........+frac{1}{100.101}voi 1 ta doc A....1Cau 3 : Cho bon so a,b,c,d sao cho a+b+c+d khac 0 . Biet frac{b+c+d}{a}frac{c+d+a}{b}frac{d+a+b}{c}frac{a+b+c}{d}k. Vay kCau 4 : so cac so nguyen am x thoa man x^{2015}left(-2right)^{2014}Cau 5; tim x,y,z biet frac{x}{y}frac{10}{9},frac{y}{z}frac{3}{4}va x-y+z78Cau 6: tap hop cac so co ba chu so chia het cho 18 va to...
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cau 1: Cho A= \(\frac{100^{2014}+2}{3}-\frac{100^{2015}+17}{9}.\)tong cac cua so cua B=-9A
Cau 2: So sanh A=\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+........+\frac{1}{100.101}\)voi 1 ta doc A....1
Cau 3 : Cho bon so a,b,c,d sao cho a+b+c+d khac 0 . Biet \(\frac{b+c+d}{a}=\frac{c+d+a}{b}=\frac{d+a+b}{c}=\frac{a+b+c}{d}=k\). Vay k=
Cau 4 : so cac so nguyen am x thoa man \(x^{2015}=\left(-2\right)^{2014}\)
Cau 5; tim x,y,z biet \(\frac{x}{y}=\frac{10}{9},\frac{y}{z}=\frac{3}{4}\)va x-y+z=78
Cau 6: tap hop cac so co ba chu so chia het cho 18 va tong cac chu so ti le voi 1;2;3 la
Cau 7: gia tri cua tong S=1.2+2.3+.....+49.50 la S=
Cho a,b,c là cac so thoa man dieu kien \(\frac{2a-b}{a+b}=\frac{b-c+a}{2a-b}=\frac{2}{3}\)
Khi đo gia tri cua bieu thuc \(P=\frac{\left(5b+4a\right)^5}{\left(5b+4c\right)^2.\left(a+3c\right)^3}\)
cho a,b,c la cac so thuc duong thoa man a+b+c=3. tim gia tri nho nhat cua
P=\(\frac{a}{a^3+b^2+c}+\frac{b}{b^3+c^2+a}+\frac{c}{c^3+a^2+b}\)
nhận được thông báo thì kéo chuột xuống xem bài giải của t ở phần duyệt bài nhé
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Cho cac so a,b,c va thoa man\(\frac{a}{a+b}+\frac{b}{b+c}+\frac{c}{c+a}=2\)Tinh gia tri bieu thuc \(P=\frac{b}{a+b}+\frac{c}{b+c}+\frac{a}{c+a}\)
cho a,b,c,d la 4 so khac 0 thoa man b^2 =ac va c^2=bd.Cmr\(\frac{a^3+b^3+c^3}{b^3+c^3+d^3}\)=\(\frac{a}{b}\)
Cau 1; chofrac{x}{2}frac{y}{5}vaxy90. So cap (x;y) thoa man laCau 2 : Cho a+db+c va a^2+d^2b^2+c^2(b,d khac 0).Khi do 4 so lap thanh ti le thuc naoCau 3 :GTLN cua phan so frac{7n-8}{2n-3}Cau 4: Cho Afrac{12}{x-15} dieu kien de 0A1 va A1Cau 5 ; tim x biet /-x-5//x510Cau 6: tap hop cac so nguyen cua x thoa man (3x^2-51)^2014(-24)^2014Cau 7: tap hop cac so thoa man /x-y/+/y+9/25/0
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Cau 1; cho\(\frac{x}{2}=\frac{y}{5}\)vaxy=90. So cap (x;y) thoa man la
Cau 2 : Cho a+d=b+c va \(a^2+d^2=b^2+c^2\)(b,d khac 0).Khi do 4 so lap thanh ti le thuc nao
Cau 3 :GTLN cua phan so \(\frac{7n-8}{2n-3}\)
Cau 4: Cho A=\(\frac{12}{x-15}\) dieu kien de 0<A<1 va A>1
Cau 5 ; tim x biet /-x-5//x=5=10
Cau 6: tap hop cac so nguyen cua x thoa man (3x^2-51)^2014=(-24)^2014
Cau 7: tap hop cac so thoa man /x-y/+/y+9/25/=0
1.cho hai phan so co tong bang -3 va tich bang 12/5. tinh tong cac nghich daao cua hai phan so do
2.cho hai phan so toi gian a/b va c/d. biet a/b+c/d E z. chung minh /b/=/d/
cho a,b>0 thoa man a+b+c=6.Tim GTNN cua \(P=\frac{a^3}{\left(a+b\right)\left(b+2c\right)}+\frac{b^3}{\left(b+c\right)\left(c+2a\right)}+\frac{c^3}{\left(c+a\right)\left(a+2b\right)},\)
Bạn cho mình hỏi là chỉ a,b > 0 hay cả a,b,c > 0 vậy
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