Thu gọn đa thức sau:(a) A = 2x^2 + x - 1/2x^2 + 5x
Giải thích
a) \(A = 2{x^2} + x - \frac{1}{2}{x^2} + 5x\)
\( = \left( {2{x^2} - \frac{1}{2}{x^2}} \right) + \left( {x + 5x} \right)\)
\( = \left( {2 - \frac{1}{2}} \right){x^2} + \left( {1 + 5} \right)x\)
\( = \frac{3}{2}{x^2} + 6x\).
b) \(B = 5xy + \frac{1}{2}{x^2}y - \frac{2}{3}xy + 2{x^2}y\)
\( = \left( {5xy - \frac{2}{3}xy} \right) + \left( {\frac{1}{2}{x^2}y + 2{x^2}y} \right)\)
\( = \left( {5 - \frac{2}{3}} \right)xy + \left( {\frac{1}{2} + 2} \right){x^2}y\)
\( = \frac{{13}}{3}xy + \frac{5}{2}{x^2}y\).