we have
\(x^{2} -5x-36\)
equate to zero
\(x^{2} -5x-36=0\)
Group terms that contain the same variable, and move the constant to the opposite side of the equation
\(x^{2} -5x=36\)
Complete the square. Remember to balance the equation by adding the same constants to each side
\(x^{2} -5x+6.25=36+6.25\)
\(x^{2} -5x+6.25=42.25\)
Rewrite as perfect squares
\((x-2.5)^{2} =42.25\)
\((x-2.5)=(+/-)\sqrt{42.25} \\ x1=2.5+6.5=x1=9\\ x2=2.5-6.5=-4\)
so
\(x^{2} -5x-36=(x+4)*(x-9)\)
therefore
the answer is
The other factor is \((x+4)\)
