Question

Complete the square on the following quadratic x2+10x+9=0

Answer 1

Given a quadratic equation $x^{2} +ax+c=0$

1. the first thing we do when we want to compete the square, is write the coefficient of x as 2 times a number.

In our case the coefficient of x is 10, so we write 10 as 2*5

2. then we write + $5^{2}$ and - $5^{2}$ to the expression:

$x^{2} +2*5*x+ 5^{2} -5^{2}+9=0$

$(x^{2} +2*5*x+ 5^{2}) -25+9=0$

$(x+5)^{2}-16=0$



Answer: $(x+5)^{2}-16=0$