Comments on: How Do You Complete the Square? http://www.classbrainmath.com/2010/03/solving-a-quadratic-equations-by-completing-the-square/ A ClassBrain site for Mathematics Sun, 27 Nov 2011 13:31:28 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: admin http://www.classbrainmath.com/2010/03/solving-a-quadratic-equations-by-completing-the-square/comment-page-1/#comment-23161 admin Sun, 09 Oct 2011 11:49:35 +0000 http://www.classbrainmath.com/?p=456#comment-23161 Simplifying 4x^2 + 3x + -6 = y Isolate the 1st 2 terms: 4x^2 + 3x + 0 = 6 Divide through by 4 to bring 1st term to x^2 x^2 + 3/4x + 0 = 6/4 Take half of the coefficient (don't forget the sign!) of the x-term, and square it. Add this square to both sides of the equation. x^2 + 3/4x + (3/8)^2 = 6/4 + (3/8)^2 Simplify x^2 + 3/4x + 9/64 = 6/4 + 9/64 Place into standard form (x + 3/8)^2 = 96/64 + 9/64 Combine Like terms (x + 3/8)^2 = 105/64 Square-root both sides, remembering the "±" on the right-hand side. Simplify as necessary. x + 3/8 = ±√105/8 Solve for x Remember that the "±" means that you have two values for x. x = -3/8 + √105/8 x = -3/8 - √105/8 Simplifying
4x^2 + 3x + -6 = y

Isolate the 1st 2 terms:
4x^2 + 3x + 0 = 6

Divide through by 4 to bring 1st term to x^2
x^2 + 3/4x + 0 = 6/4

Take half of the coefficient (don’t forget the sign!) of the x-term, and square it. Add this square to both sides of the equation.
x^2 + 3/4x + (3/8)^2 = 6/4 + (3/8)^2

Simplify
x^2 + 3/4x + 9/64 = 6/4 + 9/64

Place into standard form
(x + 3/8)^2 = 96/64 + 9/64

Combine Like terms
(x + 3/8)^2 = 105/64

Square-root both sides, remembering the “±” on the right-hand side. Simplify as necessary.
x + 3/8 = ±√105/8

Solve for x
Remember that the “±” means that you have two values for x.
x = -3/8 + √105/8
x = -3/8 – √105/8

]]> By: Figure Complete | RRVOD Action Figures http://www.classbrainmath.com/2010/03/solving-a-quadratic-equations-by-completing-the-square/comment-page-1/#comment-22945 Figure Complete | RRVOD Action Figures Wed, 05 Oct 2011 15:20:37 +0000 http://www.classbrainmath.com/?p=456#comment-22945 [...] Complete, 100[/phpbay] Can't figure out how to complete the square? I need to find y=4x^2+3x-6. I need to find the vertex a...oblems and I am [...] [...] Complete, 100[/phpbay] Can't figure out how to complete the square? I need to find y=4x^2+3x-6. I need to find the vertex a…oblems and I am [...]

]]> By: admin http://www.classbrainmath.com/2010/03/solving-a-quadratic-equations-by-completing-the-square/comment-page-1/#comment-15878 admin Thu, 16 Jun 2011 05:33:52 +0000 http://www.classbrainmath.com/?p=456#comment-15878 Thanks for the alternate method. :) Thanks for the alternate method. :)

]]> By: Chrissy http://www.classbrainmath.com/2010/03/solving-a-quadratic-equations-by-completing-the-square/comment-page-1/#comment-14102 Chrissy Thu, 19 May 2011 21:08:27 +0000 http://www.classbrainmath.com/?p=456#comment-14102 You could have just used the equation (b - 2) ². *^ that is supposed to say b over 2 squared. then you could have added whatever that equals to both sides after subtracting your k value. Then whatever was in the parenthesis before you squared it would equal (X+_)²=y you wouldn't have to foil thus saving you 2 steps. Heres how I solved it... x²+8x+10=y (subtract 10) -10=y-10 x²+8x=10-y **heres where you do the equation I showed above** (8÷2)² (4)² 16 **add to both sides** x²+8x=y-10 +16 +16 x²+8x+16=y+6 **instead of trying to find common factors that equal the equation above just use whatever you got in the ()** (x+4)²=y-6 (add 6) (x+4)²+6=y ^thats the answer you really dont have to solve with the ± considering from here you start to solve for the vertex since you just put the equation into vertex form from standard form.... vertex (-4,6) line of symmetry x= -4 TADAAA shortcut. You could have just used the equation
(b
-
2) ².

*^ that is supposed to say b over 2 squared. then you could have added whatever that equals to both sides after subtracting your k value. Then whatever was in the parenthesis before you squared it would equal (X+_)²=y you wouldn’t have to foil thus saving you 2 steps.

Heres how I solved it…

x²+8x+10=y (subtract 10)
-10=y-10
x²+8x=10-y
**heres where you do the equation I showed above**
(8÷2)²
(4)²
16
**add to both sides**
x²+8x=y-10
+16 +16
x²+8x+16=y+6
**instead of trying to find common factors that equal the equation above just use whatever you got in the ()**

(x+4)²=y-6 (add 6)
(x+4)²+6=y
^thats the answer you really dont have to solve with the ± considering from here you start to solve for the vertex since you just put the equation into vertex form from standard form….

vertex (-4,6)
line of symmetry x= -4

TADAAA shortcut.

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