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Penyelesaian - Absolute value equations

Exact form: a=2
a=2

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

|x|=|y||3a+5|=|3a+7|
x=+y(3a+5)=(3a+7)
x=y(3a+5)=(3a+7)
+x=y(3a+5)=(3a+7)
x=y(3a+5)=(3a+7)

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||3a+5|=|3a+7|
x=+y , +x=y(3a+5)=(3a+7)
x=y , x=y(3a+5)=(3a+7)

2. Solve the two equations for a

5 additional steps

(-3a+5)=(-3a+7)

Add to both sides:

(-3a+5)+3a=(-3a+7)+3a

Kumpulkan sebutan sejenis:

(-3a+3a)+5=(-3a+7)+3a

Permudahkan aritmetik:

5=(-3a+7)+3a

Kumpulkan sebutan sejenis:

5=(-3a+3a)+7

Permudahkan aritmetik:

5=7

Pernyataan ini palsu:

5=7

The equation is false so it has no solution.

14 additional steps

(-3a+5)=-(-3a+7)

Expand the parentheses:

(-3a+5)=3a-7

Subtract from both sides:

(-3a+5)-3a=(3a-7)-3a

Kumpulkan sebutan sejenis:

(-3a-3a)+5=(3a-7)-3a

Permudahkan aritmetik:

-6a+5=(3a-7)-3a

Kumpulkan sebutan sejenis:

-6a+5=(3a-3a)-7

Permudahkan aritmetik:

6a+5=7

Subtract from both sides:

(-6a+5)-5=-7-5

Permudahkan aritmetik:

6a=75

Permudahkan aritmetik:

6a=12

Divide both sides by :

(-6a)-6=-12-6

Hapuskan tanda negatif:

6a6=-12-6

Permudahkan pecahan:

a=-12-6

Hapuskan tanda negatif:

a=126

Cari faktor sepunya terbesar bagi pembilang dan penyebut:

a=(2·6)(1·6)

Faktorkan keluar dan hapuskan faktor sepunya terbesar:

a=2

3. Graph

Each line represents the function of one side of the equation:
y=|3a+5|
y=|3a+7|
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.