Question

Tính hợp lí

a)\(\dfrac{2-\dfrac{1}{3}+\dfrac{1}{4}}{2+\dfrac{1}{6}-\dfrac{1}{4}}+\dfrac{\dfrac{3}{5}-\dfrac{1}{4}+\dfrac{5}{10}}{\dfrac{1}{2}+\dfrac{3}{4}-\dfrac{2}{5}}\)

b)\(\dfrac{\dfrac{5}{79}+\dfrac{5}{83}+\dfrac{1}{17}}{\dfrac{17}{79}+\dfrac{17}{83}+\dfrac{1}{5}}\)

Answer 1

a,=\(\dfrac{\left(2-\dfrac{1}{3}+\dfrac{1}{4}\right).12}{\left(2+\dfrac{1}{6}-\dfrac{1}{4}\right).12}\)+\(\dfrac{\left(\dfrac{3}{5}-\dfrac{1}{4}+\dfrac{1}{2}\right).20}{\left(\dfrac{1}{2}+\dfrac{3}{4}-\dfrac{2}{5}\right).20}\)

=\(\dfrac{24-4+3}{24+2-3}\) +\(\dfrac{12-5+10}{10+15-8}\)(nhân từng số hạng với 12;20)

=\(\dfrac{23}{23}\)+\(\dfrac{17}{17}\) =1+1=2

b,=\(\dfrac{5.\left(\dfrac{1}{79}\right)+5.\left(\dfrac{1}{83}\right)+\dfrac{1}{17}}{17.\left(\dfrac{1}{79}\right)+17.\left(\dfrac{1}{83}\right)+\dfrac{1}{5}}\)=\(\dfrac{5.\left(\dfrac{1}{79}+\dfrac{1}{83}\right)+\dfrac{1}{17}}{17.\left(\dfrac{1}{79}+\dfrac{1}{83}\right)+\dfrac{1}{5}}\)