Tính gtri biểu thức:
P =\(\frac{5}{2.1}\)+\(\frac{4}{1.11}\)+\(\frac{3}{11.2}\)+\(\frac{1}{2.15}\)+\(\frac{13}{15.4}\)
Q =\(\left(1-\frac{1}{2}\right)\).\(\left(1-\frac{1}{3}\right)\).\(\left(1-\frac{1}{4}\right)\).... \(\left(1-\frac{1}{20}\right)\)
Giúp mị nha mina-san! :))