text: You take the coefficient of the x term, divide it by 2 and then square it.  Then add and subtract this number.\nx^2 + 6x - 13 \nThe coefficient of x is -6\n-6/2 = -3\n(-3)^2 = 9\nThus, add and subtract 9\n(x^2 - 6x + 9) -13 - 9\n= (x-3)^2 - 22\n\nIf the coefficient of x^2 is not one extra steps must be done.\nExample:\n2x^2 + 20x - 5  Put 2x^2 + 20x in parentheses\n(2x^2 + 20x) - 5  Factor a 2 from the parentheses\n2(x^2 + 10x) - 5  \nDivide the coefficient of x by 2 and then square it.  Add and subtract this number inside the parentheses.\n10/2 = 5\n5^2 = 25\n2(x^2 + 10x) - 5\n= 2(x^2 + 10x + 25 - 25) - 5  \nTake the -25 out from parentheses.  When you do this multiply the -25 by the number on the outside of the parentheses.\n2(x^2 + 10x + 25 - 25) - 5\n= 2(x^2 + 10x + 25) -25(2) - 5\n= 2(x+5)^2 - 50 - 5\n= 2(x+5)^2 - 55\nIf you can complete the square, then you do not need to use the quadratic formula.