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Penyelesaian - Absolute value equations

Exact form: a=3
a=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
|2a+7|=|2a+5|
without the absolute value bars:

|x|=|y||2a+7|=|2a+5|
x=+y(2a+7)=(2a+5)
x=y(2a+7)=(2a+5)
+x=y(2a+7)=(2a+5)
x=y(2a+7)=(2a+5)

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||2a+7|=|2a+5|
x=+y , +x=y(2a+7)=(2a+5)
x=y , x=y(2a+7)=(2a+5)

2. Solve the two equations for a

5 additional steps

(-2a+7)=(-2a+5)

Add to both sides:

(-2a+7)+2a=(-2a+5)+2a

Kumpulkan sebutan sejenis:

(-2a+2a)+7=(-2a+5)+2a

Permudahkan aritmetik:

7=(-2a+5)+2a

Kumpulkan sebutan sejenis:

7=(-2a+2a)+5

Permudahkan aritmetik:

7=5

Pernyataan ini palsu:

7=5

The equation is false so it has no solution.

14 additional steps

(-2a+7)=-(-2a+5)

Expand the parentheses:

(-2a+7)=2a-5

Subtract from both sides:

(-2a+7)-2a=(2a-5)-2a

Kumpulkan sebutan sejenis:

(-2a-2a)+7=(2a-5)-2a

Permudahkan aritmetik:

-4a+7=(2a-5)-2a

Kumpulkan sebutan sejenis:

-4a+7=(2a-2a)-5

Permudahkan aritmetik:

4a+7=5

Subtract from both sides:

(-4a+7)-7=-5-7

Permudahkan aritmetik:

4a=57

Permudahkan aritmetik:

4a=12

Divide both sides by :

(-4a)-4=-12-4

Hapuskan tanda negatif:

4a4=-12-4

Permudahkan pecahan:

a=-12-4

Hapuskan tanda negatif:

a=124

Cari faktor sepunya terbesar bagi pembilang dan penyebut:

a=(3·4)(1·4)

Faktorkan keluar dan hapuskan faktor sepunya terbesar:

a=3

3. Graph

Each line represents the function of one side of the equation:
y=|2a+7|
y=|2a+5|
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.