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The equation x^2 + 6x + k = 0 has exactly one real solution. What is the value of k?
Answer: C) 9. Set the discriminant to 0: 36 - 4k = 0, so k = 9. (The equation becomes (x + 3)^2 = 0.)
Step-by-step solution
Set the discriminant to 0: 36 - 4k = 0, so k = 9. (The equation becomes (x + 3)^2 = 0.)
Common mistake
Using b^2 + 4ac (wrong sign) or solving 36 - 4k = 0 incorrectly.
Watch: 20-second video walkthrough
What is the answer to The equation x^2 + 6x + k = 0 has exactly one real solution. What is the value of k?
Answer: C) 9. Set the discriminant to 0: 36 - 4k = 0, so k = 9. (The equation becomes (x + 3)^2 = 0.)
How do you solve it?
Set the discriminant to 0: 36 - 4k = 0, so k = 9. (The equation becomes (x + 3)^2 = 0.)
What mistake do most students make?
Using b^2 + 4ac (wrong sign) or solving 36 - 4k = 0 incorrectly.
What SAT topic is this?
Advanced Math. Practice more free Advanced Math questions with instant feedback at Syntene Learn.