Question

equação do 2 grau 4x elevado a 2=81

Answer 1

(4x)^2=81
16x^2=81
x=+-9/4

Answer 2

$4x^2 = 81 \\ x^2 = \frac{81}{4} \\ x = \pm \sqrt{\frac{81}{4}} \\ x = \pm \frac{9}{2} = \pm 4,5$