FIrst, add #color(red)(1)# to each side of the equation to isolate the #x# term while keeping the equation balanced:
#25x^2 - 1 + color(red)(1) = 48 + color(red)(1)#
#25x^2 - 0 = 49#
#25x^2 = 49#
Next, divide each side of the equation by #color(red)(25)# to isolate the #x^2# term while keeping the equation balanced:
#(25x^2)/color(red)(25) = 49/color(red)(25)#
#(color(red)(cancel(color(black)(25)))x^2)/cancel(color(red)(25)) = 49/25#
#x^2 = 49/25#
Now, take the square root of each side of the equation to solve for #x# while keeping the equation balanced. Remember, when taking the square root of a number there is a positive and negative result:
#sqrt(x^2) = +-sqrt(49/25)#
#x = +-7/5#