What is the value of k if the quadratic equation x^2 + kx + 9 = 0 has one real r

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Question: What is the value of k if the quadratic equation x^2 + kx + 9 = 0 has one real root?

Options:

Correct Answer: -3

Solution:

For one real root, the discriminant must be zero: k^2 - 4*1*9 = 0 => k^2 = 36 => k = ±6.

What is the value of k if the quadratic equation x^2 + kx + 9 = 0 has one real root?

What is the value of k if the quadratic equation x^2 + kx + 9 = 0 has one real root?

Step 1: Identify the quadratic equation, which is x^2 + kx + 9 = 0.
Step 2: Recall that a quadratic equation has one real root when its discriminant is zero.
Step 3: Write the formula for the discriminant, which is D = b^2 - 4ac. Here, a = 1, b = k, and c = 9.
Step 4: Substitute the values into the discriminant formula: D = k^2 - 4*1*9.
Step 5: Simplify the expression: D = k^2 - 36.
Step 6: Set the discriminant equal to zero for one real root: k^2 - 36 = 0.
Step 7: Solve for k by adding 36 to both sides: k^2 = 36.
Step 8: Take the square root of both sides: k = ±6.

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