Question

me ajudem
resolva as equações de 2 grau:

a) 4x²-9=0
b) 7x²-42=0
c)x²+5=0
d)x²+5=0
e)5x²-25=0

Answer 1

$a) \\ 4x^2-9=0 \\ \\ 4x^2=9 \\ \\ x^2= \frac{9}{4} \\ \\ x=\pm \sqrt{ \frac{9}{4} } \\ \\ x=\pm \frac{3}{2} \\ \\ S=\{- \frac{3}{2} ,+ \frac{3}{2}\} \\ \\ b) \\ 7x^2-42=0 \\ 7x^2=42 \\ x^2=42\div7 \\ x^{2} =6 \\ \\ x=\pm \sqrt{6} \\ \\ S=\{- \sqrt{6} ,+ \sqrt{6} \}$ 


$c)~= d) \\ \\ x^2+5=0 \\ x^2=-5 \\ x=\pm \sqrt{-5} ~~ n/~existe~~raiz \\ \\ S=\emptyset~~ conjunto~~vazio \\ \\ e) \\ 5x^2-25=0 \\ 5x^2=25 \\ x^2=25\div5 \\ x^2=5 \\ \\ x=\pm \sqrt{5} \\ \\ S=\{- \sqrt{5} ,+ \sqrt{5} \}$