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4 years ago

Solve for |2x + 4|-1=7

Mathematics

1 answer:

Rudik [331]4 years ago

6 0

Answer:

x = - 6 or x = 2

Step-by-step explanation:

The absolute value function always returns a positive value. However, the expression inside can be positive or negative.

Given

| 2x + 4 | - 1 = 7 ( add 1 to both sides )

| 2x + 4 | = 8, thus

2x + 4 = 8 ( subtract 4 from both sides )

2x = 4 ( divide both sides by 2 )

x = 2

-(2x + 4) = 8

- 2x - 4 = 8 ( add 4 to both sides )

- 2x = 12 ( divide both sides by - 2 )

x = - 6

As a check

Substitute these values into the left side of the equation and if equal to the right side then they are the solutions.

x = 2 → | 4 + 4 | - 1 = | 8 | - 1 = 8 - 1 = 7 ← True

x = - 6 → | - 12 + 4 | - 1 = | - 8 | - 1 = 8 - 1 = 7 ← True

Hence the solutions are x = - 6 or x = 2

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