Do the same thing as the attached image.
Multiply the denominator by 4
Hope you won't be turned off by a correction, but we really need to use the symbol " ^ " to denote exponentiation.
Thus, we have x^2 = 100
Taking the square root of both sides, we get x = plus or minus 10. Verify, please, that both x = -10 and x = +10 satisfy the given equation.
Just pretend it’s a 3d right angle triangle and find the length of the hypotenuse.
d = sqrt(6^2 + 10^2 + 15^2) = 19
