important question

Kiran · 2006-11-22 03:28:43

ok
if teh question asks to complete the sqaure right
and the eqaution looks like
numberX^2 - numberX - number = number or you can say zero
right
so in this eqaution do you use
quadratic formula?
it seems like you do!

Devantè · 2006-11-22 03:34:50

Well, yes, but think of it as;

ax² + bx + c = 0

Where a ≠ 0.

The equation for a quadratic formula is;

x = (-b ± √b² - 4ac)/2a

Yes, you do use the quadratic formula.

Last edited by Devanté (2006-11-22 03:35:24)

Kiran · 2006-11-22 03:38:47

ok so in my problem
4x^2 - 3x - 7 = 0
i have ot put it like so >

x = -3 +- sqrt(3^2 - 4(4)(7)) / 2(4)

Devantè · 2006-11-22 03:43:56

Yes, I'm quite sure that that's correct.

Kiran · 2006-11-22 03:46:05

ok thanks

Kiran · 2006-11-22 03:58:30

ok i got up tp

x = -3 +- sqrt-103 / 8

now what

mathsyperson · 2006-11-22 06:01:08

That's all you can do. You could divide each term on the numerator by 8 invidually, but that doesn't really make it any simpler.

However!

The question asks you to solve by completing the square, which means that you can't use the quadratic formula in the first place.

To complete the square, you need to rewrite the original equation in the form a(x+b)² = c.

You can then divide by a, square root both sides and subtract b to find your answer in terms of x.

Devantè · 2006-11-22 06:04:06

Argh, it says to complete the square? I don't know how I missed that.

Anyway, Mathsyperson is right.

Math Is Fun Forum

#1 2006-11-22 03:28:43

important question

#2 2006-11-22 03:34:50

Re: important question

#3 2006-11-22 03:38:47

Re: important question

#4 2006-11-22 03:43:56

Re: important question

#5 2006-11-22 03:46:05

Re: important question

#6 2006-11-22 03:58:30

Re: important question

#7 2006-11-22 06:01:08

Re: important question

#8 2006-11-22 06:04:06

Re: important question

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