Friday, December 7, 2012

What are the roots of the equation x^2-4x+3=0. Work on two methods.

The first method is to use
factorization:


The original equation is:
x^2-4x+3=0


We'll write 3 as the difference 4 - 1 =
3


We'll re-write the equation, changing 3 with the
difference:


x^2-4x+4-1=0


Now,
we'll combine the first and the last terms and the middle
terms:


(x^2 - 1) - (4x - 4) =
0


We'll write the difference of squares as a
product:


x^2 - 1 =
(x-1)(x+1)


We'll factorize (4x - 4) by
4:


(4x - 4) = 4(x-1)


Now,
we'll re-write the equation:


(x-1)(x+1) - 4(x-1) =
0


We'll factorize by (x-1) and we'll
get:


(x-1)(x+1-4) = 0


We'll
set each factor as zero:


x - 1 =
0


We'll add 1 both sideS:


x =
1


x - 3 = 0


We'll add 3 both
sides:


x = 3


The
roots of the equation are: {1 ;
3}. 


The second method is to
apply the quadratic formula:


x1 =
[-b+sqrt(b^2-4ac)]/2a


x1 =
[4+sqrt(16-12)]/2


x1 =
(4+2)/2


x1 =
3


x2 =
(4-2)/2


x2 =
1


As we can see, we've get the
same result!

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