L S asked in Science & MathematicsMathematics · 8 years ago

# 3|3-5r|-3=18 Any help with this one?

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• 8 years ago

|3−5r| = 7

3−5r = 7 or 3−5r = −7

r = −4/5 or 2.

• 8 years ago

Start by isolating the absolute value

|3 - 5r| = 7

Now remove the absolute value sign and solve for both positive and negative 7.

3 - 5r = 7

-5r = 4

r = -4/5

3 - 5r = -7

-5r = -10

r = 2

To check the answers, substitute both -4/5 and 2 for r in the original equation.

3|3 - 5(-4/5)| - 3 = 18

3|3 + 4| - 3 = 18

3|7| - 3 = 18

21 - 3 = 18

18 = 18

3|3 - 5(2)| - 3 = 18

3|3 - 10| - 3 = 18

3|-7| - 3 = 18

3(7) - 3 = 18

21 - 3 = 18

18 = 18

Both work

r = -4/5, 2

• Niall
Lv 7
8 years ago

Before solving for an absolute you value you will need to isolate it first, start by adding 3 to both sides:

3|3 - 5r| = 21

Now divide both sides by 3:

|3 - 5r| = 7

Now that you have isolated it you can now start to find the solution, take the absolute positive value:

3 - 5r = 7

-5r = 4

r = - 4/5

Take the absolute negative value:

3 - 5r = -7

-5r = -10

r = 2

---------------

Overall:

r = - 4/5, 2

• Mike G
Lv 7
8 years ago

3|3-5r| = 21

3-5r = ±7

-5r = 4

r = -4/5 or

-5r = -10

r = 2

r = 2 or -4/5