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Solution - Absolute value equations

Exact form: x=2.25
x=2.25

Other Ways to Solve

Absolute value equations

Step-by-step explanation

1. Rewrite the equation with one absolute value terms on each side

|x3.5|+|x+1|=0

Add |x+1| to both sides of the equation:

|x3.5|+|x+1||x+1|=|x+1|

Simplify the arithmetic

|x3.5|=|x+1|

2. Rewrite the equation without absolute value bars

Use the rules:
|x|=|y|x=±y and |x|=|y|±x=y
to write all four options of the equation
|x3.5|=|x+1|
without the absolute value bars:

|x|=|y||x3.5|=|x+1|
x=+y(x3.5)=(x+1)
x=y(x3.5)=(x+1)
+x=y(x3.5)=(x+1)
x=y(x3.5)=(x+1)

When simplified, equations x=+y and +x=y are the same and equations x=y and x=y are the same, so we end up with only 2 equations:

|x|=|y||x3.5|=|x+1|
x=+y , +x=y(x3.5)=(x+1)
x=y , x=y(x3.5)=(x+1)

3. Solve the two equations for x

6 additional steps

(x-3.5)=-(-x+1)

Expand the parentheses:

(x-3.5)=x-1

Subtract from both sides:

(x-3.5)-x=(x-1)-x

Group like terms:

(x-x)-3.5=(x-1)-x

Simplify the arithmetic:

-3.5=(x-1)-x

Group like terms:

-3.5=(x-x)-1

Simplify the arithmetic:

3.5=1

The statement is false:

3.5=1

The equation is false so it has no solution.

11 additional steps

(x-3.5)=-(-(-x+1))

NT_MSLUS_MAINSTEP_RESOLVE_DOUBLE_MINUS:

(x-3.5)=-x+1

Add to both sides:

(x-3.5)+x=(-x+1)+x

Group like terms:

(x+x)-3.5=(-x+1)+x

Simplify the arithmetic:

2x-3.5=(-x+1)+x

Group like terms:

2x-3.5=(-x+x)+1

Simplify the arithmetic:

2x3.5=1

Add to both sides:

(2x-3.5)+3.5=1+3.5

Simplify the arithmetic:

2x=1+3.5

Simplify the arithmetic:

2x=4.5

Divide both sides by :

(2x)2=4.52

Simplify the fraction:

x=4.52

Simplify the arithmetic:

x=2.25

4. Graph

Each line represents the function of one side of the equation:
y=|x3.5|
y=|x+1|
The equation is true where the two lines cross.

Why learn this

We encounter absolute values almost daily. For example: If you walk 3 miles to school, do you also walk minus 3 miles when you go back home? The answer is no because distances use absolute value. The absolute value of the distance between home and school is 3 miles, there or back.
In short, absolute values help us deal with concepts like distance, ranges of possible values, and deviation from a set value.