Question

resolver as equações incompleta do 2°grau
49x²-81=0
x²=225

Answer 1

$49x^2 -81 = 0 \\ 49x^2 = 81 \\ x^2 = \frac{81}{49} \\ x= \sqrt{ \frac{81}{49} } \\ \\ x = \pm\, \frac{9}{7}$


$x^2 = 225 \\ x = \sqrt{225} \\ \\ x = \pm15$

Answer 2

49x² = 81
x² = 81/49 
x =V81/V49  =  V9² / V7² =  9/7 *****

x² = 225
x² = 3² * 5²
x = V3² * V2²  = 3 * 2 = 6 ****