(1,0 điểm) Thực hiện phép tính: a) 27 1 5 : 8 3 − 51 1 5 . 3 8 + 19 ;b) 25. ( − 1 2 ) 2 − 2. ( − 1 2 ) 2 − 3. √ 1 16 .

a) \(27\frac{1}{5}:\frac{8}{3} - 51\frac{1}{5}.\frac{3}{8} + 19\)

\( = 27\frac{1}{5}.\frac{3}{8} - 51\frac{1}{5}.\frac{3}{8} + 19\)

\( = \left( {27\frac{1}{5} - 51\frac{1}{5}} \right).\frac{3}{8} + 19\)

\( = - 24.\frac{3}{8} + 19\)

\( = - 9 + 19\)

\( = 10.\)

b) \(25.{\left( { - \frac{1}{2}} \right)^2} - 2.{\left( { - \frac{1}{2}} \right)^2} - 3.\sqrt {\frac{1}{{16}}} \)

\( = 25.\frac{1}{4} - 2.\frac{1}{4} - 3.\sqrt {{{\left( {\frac{1}{4}} \right)}^2}} \)

\( = 25.\frac{1}{4} - 2.\frac{1}{4} - 3.\frac{1}{4}\)

\( = \left( {25 - 2 - 3} \right).\frac{1}{4}\)

\( = 20.\frac{1}{4}\)

\( = 5.\)