Question

Calcule e escreva os resultados na forma reduzida. PS: Com cálculos. a) (2y³-y).(y²-7) b) (x+2).(x²-4x+9) c) (a²b²+5ab-3).(4-ab) d) (x²y+2xy²-6xy).(x-y)

Answer 1

$a)\\ \\ (2y^{3} -y)(y^{2} -7)=2y^{5} -14y^{3} -y^{3} +7y=\\ \\ 2y^{5} -15y^{3} +7y$

$b)\\ \\ (x+2)(x^{2} -4x+9)=x^{3} -4x^{2} +9x+2x^{2} -8x+18=\\ \\ x^{3} -2x^{2} +x+18$

$c)\\ \\ (a^{2} b^{2} +5ab-3)(4-ab)=4a^{2} b^{2} +20ab-12-a^{3} b^{3} -5a^{2} b^{2} +3ab=\\ \\ -a^{2} b^{2} +23ab-12-a^{3} b^{3}$

$d)\\ \\ (x^{2} y+2xy^{2} -6xy)(x-y)=\\\\x^{3} y+2x^{2} y^{2} -6x^{2} y -x^{2} y^{2} -2xy^{3} +6xy^{2} =\\ \\ x^{3} y+x^{2} y^{2} -6x^{2} y-2xy^{3} +6xy^{2}$