Re: Quadratic Equation help

1) To complete a square isolate the constant term, multiply everything by 4 times the coeficient of x^2, square the coefficient of x and add it to both sides. It looks like this

multiply through by 4*2 = 8

add (-3)^2 = 9 to both sides

The square has been completed on the left.

Take square root

add 3

divide by 4

2) To use the popular version of the quadratic formula set the equation to 0 then identify a, b, and c then plug into the formula.

a = c^2 - 1

b = -1

c = -1

plug it in

Simplify.

:)

Re: Quadratic Equation help

Re: Quadratic Equation help

Quote:

Originally Posted by

**Caddym89** Cheers agentmulder!

I'll drink to that!

:)

1 Attachment(s)

Re: Quadratic Equation help

Re: Quadratic Equation help

Re: Quadratic Equation help

Quote:

Originally Posted by

**Caddym89** Hi there, I'm having trouble with two of the more challenging problems in my homework.

1) 2x^{2 }- 3x + 2a = 0 , this needs to be solved using complete the square method.

2) c^{2}x^{2 }- x - 1 = x^{2}, to be solved using quadratic formula.

any help would be appreciated, thanks.

While I do like Agent Mulder's version of completing the square, the more common method is to take out whatever the a term is as a factor first and complete the square on the remaining stuff.

Re: Quadratic Equation help

Thanks everyone, it's useful to know more than one method of completing the square also. My problem is making silly mistakes, I was originally stuck on this trying to figure out how to get the 16a in prove it's method, this is again not so difficult. (;