Let us begin by writing the given equation:
g² - 12g = - 36
Bringing all the terms to LHS for getting a quadratic equation,
g² - 12g + 36 = 0
Splitting the middle term,
g² - 6g - 6g + 36 = 0
Taking out common factors,
g ( g - 6 ) - 6 ( g - 6 ) = 0
Taking out common factors,
( g - 6 ) ( g - 6 ) = 0
( g - 6 )² = 0
( g - 6 ) = √0
g - 6 = 0
g = 6
Hence, after solving we get, g = 6