Violympic toán 9
Các câu hỏi tương tự
Cho a,b,c \(\in R^+\) và a.b.c=1. Chứng minh rằng:
\(\frac{a}{\left(a+1\right)\left(b+1\right)}+\frac{b}{\left(b+1\right)\left(c+1\right)}+\frac{c}{\left(c+1\right)\left(a+1\right)}\ge\frac{3}{4}\)
Cho \(x\in R\). Tìm GTNN của hàm số:
\(f\left(x\right)=\left|x-1\right|+2\left|x-2\right|+3\left|x-3\right|+4\left|x-4\right|\)
Cho \(x,y,z\in R\) và \(\left(x-y\right)\left(x-z\right)=1\) với \(y\ne z\)
CM: \(S=\frac{1}{\left(x-y\right)^2}+\frac{1}{\left(y-z\right)^2}+\frac{1}{\left(z-x\right)^2}\ge4\)
Cho ba số a,b,c dương abc=1. CMR
P = \(\dfrac{a^2}{\left(2ab+1\right)\left(ab+2\right)}+\dfrac{b^2}{\left(2bc+1\right)\left(bc+2\right)}+\dfrac{c^2}{\left(2ac+1\right)\left(ac+2\right)}\)\(\ge\)\(\dfrac{1}{3}\)
rút gọn:
\(\left(1+\tan^2\alpha\right)\left(1-\sin^2\alpha\right)-\left(1+\cot^2\alpha\right)\left(1-\cos^2\alpha\right)\)
Rút gọn :
\(\left(\sqrt{2}+1\right)\left(\sqrt{3}+1\right)\left(\sqrt{6}+1\right)\left(5-2\sqrt{2}-\sqrt{3}\right)\)
Cho a,b,c là ba số thực dương thoãm ãn \(\left(ab\right)^3+\left(bc\right)^3+\left(ca\right)^3=3\left(abc\right)^2\)
CMR : \(\left(1+\dfrac{a}{b}\right)\left(1+\dfrac{b}{c}\right)\left(1+\dfrac{c}{a}\right)=8\)
Cho a,b,c là ba số thực dương thỏa mãn abc=1.CMR
\(\dfrac{a^2}{\left(ab+2\right)\left(2ab+1\right)}+\dfrac{b^2}{\left(bc+2\right)\left(2bc+1\right)}+\dfrac{c^2}{\left(ca+2\right)\left(2ca+1\right)}\)\(\ge\)\(\dfrac{1}{3}\)
rút gọn biểu thức P=\(\dfrac{\sqrt{1+\sqrt{1-x^2}}\left[\left(1+x\right)\sqrt{1+x}-\left(1-x\right)\sqrt{1-x}\right]}{x\left(2+\sqrt{1-x^2}\right)}\)