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Mathematics

If x² - 4x = 5, the value of x is :
5
-1
5 or -1
5 and -1

Quadratic Equations

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Answer

Given,

⇒ x² - 4x = 5

⇒ x² - 4x - 5 = 0

⇒ x² - 5x + x - 5 = 0

⇒ x(x - 5) + 1(x - 5) = 0

⇒ (x + 1)(x - 5) = 0

⇒ (x + 1) = 0 or (x - 5) = 0

⇒ x = -1 or x = 5.

Hence, Option 3 is the correct option.

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