\(\left(a^3+b^3-a^3b^3\right)+27a^6b^6=\left[\left(a+b\right)^3-3ab\left(a+b\right)-a^3b^3\right]+27a^6b^6\)
Thay ab=a+b, ta có:
\(=\left(a^3b^3-3a^2b^2-a^3b^3\right)+27a^6b^6\)
\(=27a^6b^6-3a^2b^2\)
Cho \(a+b=ab\). Tính giá trị biểu thức: \(A=(a^3+b^3-a^3b^3)+27a^6b^6\).
Cho a và b thỏa mãn :
\(\left\{{}\begin{matrix}a^3-6a^2+15a=9\\b^3-3b^2+6b=-1\end{matrix}\right.\)
Tính \(\left(a-b\right)^{2014}\)
Cho a,b,c là các số thực dương. Chứng minh rằng:
\(\dfrac{3a^3+7b^3}{2a+3b}+\dfrac{3b^3+7c^3}{2b+3c}+\dfrac{3c^3+7a^3}{2c+3a}\ge3\left(a^2+b^2+c^2\right)-\left(ab+bc+ca\right)\)
\(\frac{2.\left(ab+bc+ca\right)^2}{3ab^3+a^3b+cb^3+3c^3b+ac^3+3a^3c}=\frac{a+b+c}{2}\)
Cho 2 số thực a , b . CMR \(2\left(a^4+b^4\right)\ge ab^3+a^3b+2a^2b^2\)
1. Rút gọn \(A=\frac{\sqrt{14+6\sqrt{5}}-\sqrt{14-6\sqrt{5}}}{\sqrt{\left(\sqrt{5}+1\right)\cdot\sqrt{6-2\sqrt{5}}}}\)
2.Tính a) \(B=\left(\sqrt[3]{2}+1\right)^3\cdot\left(\sqrt[3]{2}-1\right)^3\)
b)Tìm C=\(a^3b-ab^3\) với \(a=\frac{6}{2\sqrt[3]{2}-2+\sqrt[3]{4}}\); \(b=\frac{2}{2\sqrt[3]{2}+2+\sqrt[3]{4}}\)
3. Giải \(\left|x^2-x+1\right|-\left|x-2\right|=6\)
Cho a,b,c>0. Chứng minh rằng:
\(\frac{a^6}{b^3\left(c+a\right)}+\frac{b^6}{c^3\left(a+b\right)}+\frac{c^6}{a^3\left(b+c\right)}\ge\frac{ab+bc+ca}{2}\)
\(\sqrt{\frac{bc}{a\left(3b+a\right)}}+\sqrt{\frac{ac}{b\left(3c+b\right)}}+\sqrt{\frac{ab}{c\left(3a+c\right)}}\ge\frac{3}{2}\)
\(\frac{ab}{c^3\left(1+a\right)\left(1+b\right)}+\frac{bc}{a^3\left(1+b\right)\left(1+c\right)}+\frac{ca}{b^3\left(1+c\right)\left(1+a\right)}\)<= 1/6
cho ab+bc+ca=abc