Advanced Math practice question

Answer: -13 or −13

Factor 2 from the x-terms: 2(x² + 6x) + 5. Complete the square inside: x² + 6x = (x + 3)² − 9. So the expression is 2((x + 3)² − 9) + 5 = 2(x + 3)² − 18 + 5 = 2(x + 3)² − 13. Thus k = −13.

Common wrong answers

If you answered 3

3 is h, the number inside the parentheses. The question asks for k, the constant outside.

If you answered -4

−4 is 5 − 9, subtracting the 9 only once. The 9 is inside a bracket multiplied by 2, so it becomes 18.

If you answered -31

−31 is 5 − 36, using (6)² = 36 instead of (6/2)² = 9 for the square.

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