Question

Obtenha as raízes das equações a seguir
A) x²+6x=0
B)x²-81=0
C)3x²-15x=0
D)4x²-256=0

Answer 1

$a) \\ x^{2} +6x=0 \\ \\ x(x+6)=0 \\ \\ x+6=0~~~~~~x=0 \\ x=-6 \\ \\ S=\{-6,0\} \\ \\ b) \\ x^{2} -81=0 \\ x^{2} =81 \\ x=\pm \sqrt{81} \\ \\ x=\pm9 \\ \\ S=\{-9,+9\} \\ \\ c) \\ 3x^2-15x=0 \\ x(3x-15)=0 \\ \\ 3x-15=0~~~~~~x=0 \\ 3x=15 \\ x=15\div3 \\ x=5 \\ \\ S=\{0,5\} \\ \\ d) \\ 4x^2-256=0 \\ 4x^2=256 \\ x^{2} =256\div4 \\ x^{2} =64 \\ x=\pm \sqrt{64} \\ x=\pm8 \\ \\ S=\{-8,+8\}$