Question

Tính nhanh :

\(\dfrac{64x50+44x100}{27x38+146x19}\)

\(\dfrac{1}{7}+\dfrac{1}{8}+\dfrac{1}{9}+\dfrac{1}{10}+\dfrac{1}{11}+\dfrac{1}{12}+\dfrac{1}{14}+\dfrac{1}{15}+\dfrac{1}{18}+\dfrac{1}{22}+\dfrac{1}{24}+\dfrac{1}{28}+\dfrac{1}{33}\)

Answer 1

a: \(=\dfrac{50\left(64+2\cdot44\right)}{19\left(27\cdot2+146\right)}=\dfrac{50\cdot152}{19\cdot200}=2\)

b:

1/7+1/14+1/28=1/4

1/8+1/12+1/24=1/4

1/11+1/22+1/33=1/6

1/9+1/18=1/6

=>1/10+1/13+1/15+1/2+1/3 =14/13