Hey there!
Assuming you meant
[tex] 5r^2 - 12 = 68 [/tex]
If so, follow these steps so it can be a little bit easier to solve
Firstly, we have to [tex] add [/tex] by [tex] 12 [/tex] on each of your sides
[tex] 5r^2 -12 +12 \\ \\ 68 + 12 [/tex]
[tex] 5r^2 = 5r^2 \\ \\ 68 + 12 = 80 [/tex]
We get: [tex] 5r^2 =80 [/tex]
Now, we have [tex] divide [/tex] by [tex] 5 [/tex] on each of your sides
[tex] \frac{5r^2}{5} = \frac{80}{5} [/tex]
[tex] \frac{80}{5} = 16 [/tex]
We get: [tex] r^2 = 16 [/tex]
[tex] r = [/tex] ± [tex] \sqrt{16} [/tex]
Therefore , your answer is:[tex] r = [/tex] ±[tex] 4 [/tex]
Good luck on your assignment and enjoy your day!
~[tex] LoveYourselfFirst:) [/tex]
