First, subtract color(red)(3) from each side of the equation to isolate the a term while keeping the equation balanced:
a^2 + 3 - color(red)(3) = 51 - color(red)(3)
a^2 + 0 = 48
a^2 = 48
Now, take the square root of each side of the equation to solve for a while keeping the equation balanced. Remember, the square root of a number produces a positive and negative result:
sqrt(a^2) = +-sqrt(48)
a = +-sqrt(48)
We can rewrite the radical and simplify using this rule for radicals:
sqrt(color(red)(a) * color(blue)(b)) = sqrt(color(red)(a)) * sqrt(color(blue)(b))
a = +-sqrt(16 * 3)
a = +-sqrt(16) * sqrt(3)
a = +-4sqrt(12)
If necessary, the numerical answer is:
a = +-6.928 rounded to the nearest thousandth