Advanced Math practice question

Answer: -6 or −6

(x² − 16) + (x² − 8x + 16) = 2x² − 8x, so a = 2, b = −8, c = 0, and a + b + c = −6. (Shortcut: at x = 1 the expression is (−3)(5) + 9 = −6.)

Common wrong answers

If you answered 2

2 is a alone.

If you answered 6

6 has the wrong sign on b.

If you answered -38

−38 keeps both constants as −16 and forgets they cancel: 2 − 8 − 32.

More Advanced Math questions

• Hard
  A population of bacteria doubles every 3 hours. If it starts at 500, which function models the population P af…
• Hard
  How many real solutions does x² + 4x + 5 = 0 have?
• Hard
  A car worth $20,000 loses 15% of its value each year. What is its value after 2 years?
• Hard
  An investment of $1,000 grows at 6% per year, compounded annually. Which expression gives its value after t ye…
• Hard
  If f(x) = x² − 1 and g(x) = x + 2, what is g(f(3))?
• Hard
  The parabola y = x² − 8x + 12 crosses the x-axis at two points. What is the x-coordinate of the vertex?