Friday, April 22, 2011

What is x if 4 | 2x-6 | + 8 = 12

We'll solve the absolute value equation as it
follows:


4 | 2x-6 | + 8 =
12


We'll first subtract 8 both sides in order to isolate
the absolute value to the left side:


4 | 2x-6 |  = 12 -
8


4 | 2x-6 |   = 4


We'll
divide by 4:


| 2x-6 |  =
1


We'll get 2 cases to
solve:


1) We'll impose the constraint of absolute
value:


2x-6>=0


2x>=6


x>=3


Now,
we'll solve the equation:


2x-6 =
1


We'll add 6 both sides:


2x =
7


x = 7/2 = 3.5 > 3


The
value of x belongs to the interval of admissible
values:


[7/2 , +inf.)


2)
2x-6<0


2x<6


x<3


Now,
we'll solve the equation:


2x-6 =
-1


We'll subtract 6 both
sides:


2x = 5


We'll divide by
2:


x = 5/2


Since the value of
x belongs to the interval of admissible values, x = 2/5 is also a root of the given
equation.


Since both values of x respect the
constraints of the modulus, they represent solutions of the equation: {5/2 ;
7/2}.

No comments:

Post a Comment

What accomplishments did Bill Clinton have as president?

Of course, Bill Clinton's presidency will be most clearly remembered for the fact that he was only the second president ever...