Beginning & Intermediate Algebra
Because square roots are treated like variables in addition; you combine their outside coefficients (1 + 1 = 2), but the number inside remains unchanged.
Because 7 + 7 is 14, and the rules of radicals require you to pull a 2 to the outside to balance the equation.
Because adding identical numbers inside a square root requires you to square the outside coefficient.
Because square roots can only be combined by adding the inside numbers if they are perfect squares.