Expert: NUR ARINA BASILAH BINTI KAMISAN - 8/23/2008

Question
x^2 +3x- 7/4=0

solve equation by completing the square

Answer
dear ashlee,

x^2+3x-7/4=0
you must know the basic formula for completing the square.
when you have ax^2+bx+c=0
then the completing rule is (x+b/2a)^2+c-(b/2a)^2=0 or we also can write it like this:
(x+b/2a)^2=-c+(b/2a)^2

so now your equation will become
(x+3/2)^2-(7/4)-(3/2)^2=0
(x+3/2)^2-(7/4)-(9/4)=0
(x+3/2)^2-16/4=0
(x+3/2)^2-4=0
(x+3/2)^2=4
x+3/2=squareroot(4)
x+3/2=2 or x+3/2=-2
x=1/2 or x=-7/2

or you also can see this website for more detail:
http://www.purplemath.com/modules/sqrquad.htm

good luck!!!