a) \(\frac{2005\cdot2006-1}{2006\cdot2004+2005}\)
\(=\frac{2004\cdot2006+2006-1}{2006\cdot2004+2005}\)
\(=1\)
b) \(27\left(\frac{171717}{272727}+\frac{373737}{363636}\right)\)
\(=27\left(\frac{17}{27}+\frac{37}{36}\right)\)
\(=27\cdot\frac{17}{27}+27\cdot\frac{37}{36}\)
\(=17+\frac{9\cdot3\cdot37}{9\cdot4}\)
\(=17+27,75=44,75\)
P/s : ko biết câu b có đúng ko nữa