So sánh các biểu thức A và B, biết:
a/ A = \(\frac{19}{41}+\frac{23}{53}+\frac{29}{61}\) B = \(\frac{21}{41}+\frac{23}{49}+\frac{33}{65}\)
b/ A = \(\frac{12}{14^{11}}+\frac{23}{14^{12}}\) B = \(\frac{12}{14^{12}}+\frac{23}{14^{11}}\)
c/ A = \(\frac{19^{20}+5}{19^{20}-8}\) B = \(\frac{19^{21}+6}{19^{21}-7}\)
1 a<b
2a=b
3a>b
\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)