Respuesta :

PunIntended

Add 12 to both sides:

5r^2 = 80

Divide by 5:

r^2 = 16

Square root both sides:

r = +/- 4

The answer is {+/- 4}.

coolcat3390
5r2-12=68
+12 +12
5r2 = 80
-80
5r2 -80 = 0
÷5 ÷5 ÷5

r2 -16 = 0
+16 +16
r2 = 16

root: r2 = root: 16
r = {+/- 4}
Ver imagen coolcat3390