Solve for a: [9(r^2) +9(a^2)]=35?

9r^2 + 9a^2 = 35
r^2 + a^2 = 35/9
a^2 = (35/9) - r^2
a = +/- sqrt((35/9) - r^2)

hope this helps! :)

9r^2 + 9a^2 = 35
9a^2 = -9r^2 + 35
a^2 = (-9r^2 + 35)/9
a = ±√[(-9r^2 + 35)/9]
a = [±√(-9r^2 + 35)]/3

9a^2=35-9r^2
a=+ & -(35-9r^2)/9^1/2=+ & - [(35-9r^2)^1/2]/3

[9(r^2) +9(a^2)]=35 (Divide the whole equation by 9) So:
r^2 + a^2 = 35/9 (Then send the r^2 to the other side)
a^2 = 35/9 - r^2 (then use the square root property to get "a" by itself)
a= +/- Square Root of ((35/9) - r^2)

robin is right