Thực hiện phép tính:
a. \(\left( {{1 \over 2}x - 1} \right)\left( {2x - 3} \right)\)
b. \(\left( {x - 7} \right)\left( {x - 5} \right)\)
c. \(\left( {x - {1 \over 2}} \right)\left( {x + {1 \over 2}} \right)\left( {4x - 1} \right)\)
Advertisements (Quảng cáo)
a. \(\left( {{1 \over 2}x - 1} \right)\left( {2x - 3} \right))\\({x^2} - {3 \over 2}x - 2x + 3 = {x^2} - {7 \over 2}x + 3\)
b. \(\left( {x - 7} \right)\left( {x - 5} \right)\)\( = {x^2} - 5x - 7x + 35 = {x^2} - 12x + 35\)
c. \(\left( {x - {1 \over 2}} \right)\left( {x + {1 \over 2}} \right)\left( {4x - 1} \right)\)\( = \left( {{x^2} + {1 \over 2}x - {1 \over 2}x - {1 \over 4}} \right)\left( {4x - 1} \right)\)
\( = \left( {{x^2} - {1 \over 4}} \right)\left( {4x - 1} \right) = 4{x^3} - {x^2} - x + {1 \over 4}\)