13 - 11
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\( A=\frac{1+13+13^2+...+13^{13}}{1+13+13^2+...+13^{12}}\) và \(B=\frac{1+11+11^2+...+11^{13}}{1+11+11^2+...+11^{12}}\) chứng minh A > B
13/19 x23/11 -13/19 x 8/11 - 13/19 x 4/11
13/19x23/11-13/19x8/11-13/19x4/11
=(23/11-8/11-4/11)=11/11=1
=13/19x1
=13/19
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tính nhanh: (4/5-4/11+4/13)/(9/5-9/11+9/13)+(5/7+5/11-5/13)/(9/7+9/11-9/13)
ta có \(\frac{\frac{4}{5}-\frac{4}{11}+\frac{4}{13}}{\frac{9}{5}-\frac{9}{11}+\frac{9}{13}}+\frac{\frac{5}{7}+\frac{5}{11}-\frac{5}{13}}{\frac{9}{7}+\frac{9}{11}-\frac{9}{13}}\)
\(=\frac{4\left(\frac{1}{5}-\frac{1}{11}+\frac{1}{13}\right)}{9\left(\frac{1}{5}-\frac{1}{11}+\frac{1}{13}\right)}+\frac{5\left(\frac{1}{7}+\frac{1}{11}-\frac{1}{13}\right)}{9\left(\frac{1}{7}+\frac{1}{11}-\frac{1}{13}\right)}\)
\(=\frac{4}{9}+\frac{5}{9}=\frac{9}{9}=1\)
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13/19 * 23/11 -13/19 * 8/11 - 13/19 * 4/11
\(\frac{13}{19}\cdot\frac{23}{11}-\frac{13}{19}\cdot\frac{8}{11}-\frac{13}{19}\cdot\frac{4}{11}=\frac{13}{19}\cdot\left(\frac{23}{11}-\frac{8}{11}-\frac{4}{11}\right)\)
\(=\frac{13}{19}\cdot1=\frac{13}{19}\)
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(3/13:11/6+3/13:11/5)-2/13+1/13
Nếu 11+11=4; 12+12=9 thì 13+13=?
Nếu 11+11=4; 12+13=12; thì 21+14=?
a/16
b/15
tui tick cậu rùi c5u tick tui nha
Nguyễn Hương Giang
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Nguyễn Hương Giang tự hỏi tự trả lời!!!
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3/13 x 6/11 + 3/13 x 9/11 - 3/13 x 4/11 = ?
Nhanh giúp mình ạ
Tính giá trị của biểu thức : \(\frac{\sqrt{13}+\sqrt{11}}{\sqrt{13}-\sqrt{11}}+\frac{\sqrt{13}-\sqrt{11}}{\sqrt{13}+\sqrt{11}}\).
\(=\frac{\left(\sqrt{13}+\sqrt{11}\right)^2+\left(\sqrt{13}-\sqrt{11}\right)^2}{\left(\sqrt{13}-\sqrt{11}\right)\left(\sqrt{13}+\sqrt{11}\right)}\)
\(=\frac{13+2\sqrt{143}+11+13-2\sqrt{143}+11}{13-11}\)
\(=\frac{48}{2}=24\)
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-4/3 - 5/7 + 4/3 3/13 x 6/11 + 3/13 x 9/11 - 3/13 x 4/11
\(\dfrac{-4}{3}-\dfrac{5}{7}+\dfrac{4}{3}=\left(\dfrac{4}{3}+\dfrac{-4}{3}\right)-\dfrac{5}{7}=0-\dfrac{5}{7}=-\dfrac{5}{7}\)
\(\dfrac{3}{13}\cdot\dfrac{6}{11}+\dfrac{3}{13}\cdot\dfrac{9}{11}-\dfrac{3}{13}\cdot\dfrac{4}{11}=\dfrac{3}{13}\cdot\left(\dfrac{6}{11}+\dfrac{9}{11}-\dfrac{4}{11}\right)=\dfrac{3}{13}\cdot1=\dfrac{3}{13}\)
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1/3-3/5+5/7-7/9+9/11-11/13+13/15+11/13-9/11+7/9-5/7+3/5-1/3
