Answer:
The number to be added to complete the square is (13/2)^2
But the solved value for x are:
x = 11.71 or -1.28
Step-by-step explanation:
x ^ 2 + 13x + 15 = 0
x^2 + 13x = -15
(The coefficient of x^2 is 1, hence needless diving through)
Add the square of half the coefficient of x to both sides
x^2 + 13x + (13/2)^2 = -15 + ( 13/2)^2
(x + 13/2)^2 = -15 + 169/4
(x + 13/2)^2 = 109/4
Take the square of both sides
x + 13/2 = +-10.44/ 2
x = 10.44/2 + 13 /2
x = 23.44/2
x = 11.71
OR
x = 10.44/2 - 13/2
x = -2.56/2
x = -1.28
Therefore x = 11.71 or -1.28
But the number to be added to complete the square is (13/2)^2
Lets keep learning, maths is fun
