Thực hiện phép tính (a) (x−1/2)^2.
Giải thích
a) \[\,\,\,{\left( {x - \frac{1}{2}} \right)^2}\]
\[ = {x^2} - 2.x.\frac{1}{2} + {\left( {\frac{1}{2}} \right)^2}\]
\[ = {x^2} - x + \frac{1}{4}.\]
b) \[\,\,\,\left( {6{a^3}{b^4} - {a^2}{b^3} + 15{a^2}{b^2}} \right):\left( {3a{b^2}} \right)\]
\[ = 6{a^3}{b^4}:\left( {3a{b^2}} \right) - {a^2}{b^3}:\left( {3a{b^2}} \right) + 15{a^2}{b^2}:\left( {3a{b^2}} \right)\]
\[ = 2{a^2}{b^2} - \frac{1}{3}ab + 5a.\]
c) \[\,\,\,\left( {2x + 1} \right)\left( {5{x^2} - 2x + 1} \right)\]
\[ = 10{x^3} - 4{x^2} + 2x + 5{x^2} - 2x + 1\]
\[ = 10{x^3} + {x^2} + 1.\]