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bình luận
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T6
ukm, mjh dang hc cái này
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bình luận
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Bài 2
To review, I will report later
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bình luận
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Bài 2
To I review, I will report later
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bình luận
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Bài 2
sorry, mistake
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bình luận
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T6
U make by english, please
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bình luận
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T7
You make by english, please
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đặt câu hỏi
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T11
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Let ABC be a triangle with the altitudes AA' , BB' , CC' meet at H. Prove that:
$\frac{HA}{HA'}+\frac{HB}{HB'}+\frac{HC}{HC'}=6\sqrt3\geq6+\frac{a}{HA'}+\frac{b}{HB'}+\frac{c}{HC'}$
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đặt câu hỏi
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T10
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For a given positive integer n, how many n-digit natural numbers can be formed from five positive digits 1,2,3,4 and 5 so that an odd numbers of 1 and even numbers of 2 are used
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đặt câu hỏi
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T9
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Let a,b,c be positive real numbers. Prove that:
$min\left\{\frac{ab}{c^2}+\frac{bc}{a^2}+\frac{ca}{b^2} {};\frac{a^2}{bc}+\frac{b^2}{ca}+\frac{a^2}{ab} \right\}\geq max\left\{\frac{a}{b}+\frac{b}{c}+\frac{c}{a} {};\frac{a}{c}+\frac{c}{b}+\frac{b}{a} \right\}$
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đặt câu hỏi
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T8
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Let Oxyz be a right trihedral with angle at O, and A,B,C move on the sides Ox, Oy and Oz respective so that the area of the triangle ABC is constant S. Let S1,S2, S3 be the areas of the triangles OBC, OCA, OAB respectively. find the greatest value of the expression:
$P=\frac{S_1}{S+2S_1}+\frac{S_2}{S+2S_2}+\frac{S_3}{S+2S_3}$
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đặt câu hỏi
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T7
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Does there exist a polynormial $P(x)$ of degree 2010 such that $P(x^2-2010)$ is divisible to $P(x)$
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đặt câu hỏi
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T6
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Solve the equation:
$3x^4-4x^3=1-\sqrt{(1+x^2)^3}$
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