If 4 is a root of the equation x 2 + kx - 4 = 0; the value of k is : 1. 3 2. -3 3. 2 4. -2

Since, 4 is the root of the equation x 2 + kx - 4 = 0. ∴ It will satisfy the equation x 2 + kx - 4 = 0. ∴ 4 2 + 4k - 4 = 0 ⇒ 16 + 4k - 4 = 0 ⇒ 4k + 12 = 0 ⇒ 4k = -12 ⇒ k = - = -3. Hence, Option 2 is the correct option.

Mathematics

If 4 is a root of the equation x² + kx - 4 = 0; the value of k is :
3
-3
2
-2

Quadratic Equations

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Answer

Since, 4 is the root of the equation x² + kx - 4 = 0.

∴ It will satisfy the equation x² + kx - 4 = 0.

∴ 4² + 4k - 4 = 0

⇒ 16 + 4k - 4 = 0

⇒ 4k + 12 = 0

⇒ 4k = -12

⇒ k = - $\dfrac{12}{4}$ = -3.

Hence, Option 2 is the correct option.

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If 4 is a root of the equation x² + kx - 4 = 0; the value of k is :
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Quadratic Equations

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