Tính tổng:
a) \({\rm{}}{x^2} + 5{{\rm{x}}^2} + ( - 3{{\rm{x}}^2})\)
b) \(5{\rm{x}}{y^2} + {1 \over 2}x{y^2} + {1 \over 4}x{y^2} + \left( { - {1 \over 2}} \right)x{y^2}\)
c) \(3{{\rm{x}}^2}{y^2}{z^2} + {{\rm{x}}^2}{y^2}{z^2}\)
a) \({\rm{}}{x^2} + 5{{\rm{x}}^2} + ( - 3{{\rm{x}}^2}) \)
\(= (1 + 5 - 3){x^2} \)
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\(= 3{{\rm{x}}^2}\)
b) \(5{\rm{x}}{y^2} + {1 \over 2}x{y^2} + {1 \over 4}x{y^2} + \left( { - {1 \over 2}} \right)x{y^2} \)
\(= \left( {5 + {1 \over 2} + {1 \over 4} - {1 \over 2}} \right)x{y^2} \)
\(= {{11} \over 2}x{y^2}\)
c) \(3{{\rm{x}}^2}{y^2}{z^2} + {{\rm{x}}^2}{y^2}{z^2} \)
\(= \left( {1 + 3} \right){{\rm{x}}^2}{y^2}{z^2} \)
\(= 4{{\rm{x}}^2}{y^2}{z^2}\)