Question

lxl+5=18

Answer 1

+13,-13

Answer 2

|x|+5=18
Subtract 5 from both sides,
|x|=13
Then you solve this in two different ways.
The first one is more analytical. You are being asked for a number whose absolute value is 13. You know that the absolute value of a negative number is the same as that of a positive number. Then, there are two numbers whose absolute values are 13, which are 13 and -13, so x={-13,13}
Or you could use the property that
\[\left| x \right|^2=x^2\]
So you'd square both sides of the second equation ( |x|=13 )
\[x^2=13^2\]
Therefore
\[x=\pm \sqrt{13^2}\]
\[x=\pm 13\]

Answer 3

thanks