Cho \(\frac{a}{b}=\frac{b}{c}=\frac{c}{2011}=\frac{2011}{a}\) và \(a+b+c\ne-2011\). Tính \(a+b-c\)

Chứng minh rằng : \(27^{20}+3^{61}+9^{31}\) chia hết cho 13

Tìm x

\(\left(x-0,2\right)^3=0,027\)

Tìm x biết

1)\(\frac{1}{3}x-\frac{2}{5}=\frac{1}{3}\)

2) \(2,5\) : \(7,5=x\) : \(\frac{3}{5}\)

3) \(x-2\sqrt{x}=0\)

4) \(\left|x\right|+\left|x+2\right|=0\)

5) \(\left|x+\frac{3}{5}\right|-\left|x-\frac{7}{3}\right|=0\)

6) \(\left(2x-1\right)^6=\left(2x-1\right)^8\)

7) \(3^{x-1}+5.3^{x-1}=162\)

8) \(\frac{37-x}{x+13}=\frac{3}{7}\)

9) \(13\frac{1}{3}:1\frac{1}{3}=26:\left(2x-1\right)\)

10) \(5-\left|1-2x\right|=3\)

Biết \(\widehat{BAC}+\widehat{xBA}+\widehat{ACy}=360^0\). Chứng minh rằng \(Bx\)|| \(Cy\)