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Penyelesaian - Absolute value equations

Exact form: x=3
x=-3

Other Ways to Solve

Absolute value equations

Penjelasan langkah demi langkah

1. 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
|3x+7|=|3x+11|
without the absolute value bars:

|x|=|y||3x+7|=|3x+11|
x=+y(3x+7)=(3x+11)
x=y(3x+7)=(3x+11)
+x=y(3x+7)=(3x+11)
x=y(3x+7)=(3x+11)

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||3x+7|=|3x+11|
x=+y , +x=y(3x+7)=(3x+11)
x=y , x=y(3x+7)=(3x+11)

2. Solve the two equations for x

5 additional steps

(3x+7)=(3x+11)

Subtract from both sides:

(3x+7)-3x=(3x+11)-3x

Kumpulkan sebutan sejenis:

(3x-3x)+7=(3x+11)-3x

Permudahkan aritmetik:

7=(3x+11)-3x

Kumpulkan sebutan sejenis:

7=(3x-3x)+11

Permudahkan aritmetik:

7=11

Pernyataan ini palsu:

7=11

The equation is false so it has no solution.

12 additional steps

(3x+7)=-(3x+11)

Expand the parentheses:

(3x+7)=-3x-11

Add to both sides:

(3x+7)+3x=(-3x-11)+3x

Kumpulkan sebutan sejenis:

(3x+3x)+7=(-3x-11)+3x

Permudahkan aritmetik:

6x+7=(-3x-11)+3x

Kumpulkan sebutan sejenis:

6x+7=(-3x+3x)-11

Permudahkan aritmetik:

6x+7=11

Subtract from both sides:

(6x+7)-7=-11-7

Permudahkan aritmetik:

6x=117

Permudahkan aritmetik:

6x=18

Divide both sides by :

(6x)6=-186

Permudahkan pecahan:

x=-186

Cari faktor sepunya terbesar bagi pembilang dan penyebut:

x=(-3·6)(1·6)

Faktorkan keluar dan hapuskan faktor sepunya terbesar:

x=3

3. Graph

Each line represents the function of one side of the equation:
y=|3x+7|
y=|3x+11|
The equation is true where the two lines cross.

Mengapa belajar ini

Learn more with Tiger

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.