Please help!Solution of the equation?

Question

Decide whether the give number is a solution of the equation


|3x+8| = 20; -4



|6+3x|=0;-2



How do i know? please explain

Thank you :)

Answer 1

Just substitute the given answer (-4 and -2), into the given equation.

|3(-4) + 8|
|-12 + 8|
|-4| = 4

4 isn't 20, so there you go. -4 doesn't work.

The | | just means absolute value, which means you consider just the number, not the sign. Basically everything negative becomes positive, and everything positive stays positive.

In the case of the second equation, it looks like -2 works out to be right.

Answer 2

|x| = absolute value of x, which means the absolute distance of x from 0, neglecting whether x is a negative or a positive number.

if x<0 then |x|=-x
if x=0 then |x|=0
if x>0 then |x|=x

For example |5|=5; |0|=0; |-3|=3
This means that |x| is always greater than 0 or equals to 0, but can't have the value of a negative number.

Replacing x=-4 to the equation
|3x+8| = 20
|3(-4)+8| = 20
|-12+8| = 20
|-4|= 20
4=20
False, -4 is not a solution of the equation.

Replacing x=-2 to the equation
|6+3x|=0
|6+3(-2)|=0
|6-6|=0
|0|=0
0=0
True, -2 is a solution of the equation.

Answer 3

To determine if something is a solution, just plug it in and see if your statement is true. In these cases:

|3(-4)+8|=20
|-12+8|=20
|-4|=20
4 = 20 FALSE, so this is not a solution.

|6 + 3x| = 0
|6 + 3(-2)| = 0
|6 + -6| = 0
|0| = 0
0 = 0 TRUE, so this is a solution.

Answer 4

Subsitute in and evaluate:

|3(-4) + 8| = |-12+8| = |-4| = 4, not a solution since we wanted a result of 20.

|6 + 3(-2)| = |6 + (-6)| = |0| = 0, this is a solution.

Answer 5

i guess substitute x=-4 and x=-2 respectively to check if it is equal to 20 or 0

Answer 6

Just plug in the number where the x is, so:
l3x+8l=20
l3(-4)+8l=20
l-12+8l=20
l-4l=20
4=20. therefore -4 is not a solution