# Thread: How do you solve a quadratic equation by completing the square if the x coeff is odd

1. ## How do you solve a quadratic equation by completing the square if the x coeff is odd

Hi guys basically I'm trying to solve the following equation by completing the square...

x2-3x-5=0

However, when I try and form the square and complete it I seem to run into trouble

(x-1.5)(x-1.5)=x2-3x+2.25

(x-1.5)2-7.25=0

(x-1.5)2=7.25

x-1.5= (root 29) divided by 2

Then I get kinda stuck. Is this right so far? Can someone please guide me through what to do? Thanks very much for any help.

2. ## Re: How do you solve a quadratic equation by completing the square if the x coeff is

Originally Posted by MattA147
Hi guys basically I'm trying to solve the following equation by completing the square...

x2-3x-5=0

However, when I try and form the square and complete it I seem to run into trouble

(x-1.5)(x-1.5)=x2-3x+2.25

(x-1.5)2-7.25=0

(x-1.5)2=7.25

x-1.5= (root 29) divided by 2

Then I get kinda stuck. Is this right so far? Can someone please guide me through what to do? Thanks very much for any help.

(x-1.5)^2 =7.25
$\displaystyle \\x^2-3x-5=0\\x^2-3x+(1.5)^2=5+(1.5)^2\\(x-1.5)^2=7.25$
$\displaystyle x=1.5\pm\sqrt{7.25}$