Question

Solve the quadratic equation by taking square roots.

1. 2x 2 - 16 = 0



2. -5x2 + 9 = 0



3. 6x2 - 15 = 27

Answer 1

see explanation

Explanation:

1

Given

2x² - 16 = 0 ( add 16 to both sides )

2x² = 16 ( divide both sides by 2 )

x² = 8 ( take the square root of both sides )

x = ±
`√(8)` = ± 2
`√(2)`

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2

Given

- 5x² + 9 = 0 ( subtract 9 from both sides )

- 5x² = - 9 ( divide both sides by - 5 )

x² =
`(9)/(5)` ( take the square root of both sides )

x = ±
`\sqrt{(9)/(5) }` = ±
`(3)/(√(5) )`

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3

Given

6x² - 15 = 27 ( add 15 to both sides )

6x² = 42 ( divide both sides by 6 )

x² = 7 ( take the square root of both sides )

x = ±
`√(7)`