Question 1054152
Completing the squares (you don't have to worry whether the quadratic will factor or not, this ALWAYS works):
x*(x+6) = 216
x^2+6x = 216
take 1/2 of the factor of x and square it:
The factor of x is 6, 6/2 = 3 and 3^2 = 9
x^2+6x+9 = 216+9
(x+3)^2 = 225
x+3 = +-sqrt225 = +-15
x = -3-15 or x = -3+15
x = -18 or x = 12
Since we are not looking for a negative number, throw away the -18 and take the 12:
12*(12+6) = 12*18 = 216 this answer is correct.
:
John