Advanced Math practice question

Answer: 6

The quadratic formula gives x = (6 ± √(36 − 16))/2 = 3 ± √5. Adding the two: (3 + √5) + (3 − √5) = 6. (For x² + bx + c = 0, the solutions always sum to −b.)

Common wrong answers

If you answered 3

3 is half the sum — the x-coordinate of the vertex, or the '3' in 3 ± √5. The two solutions together sum to 6.

If you answered 4

4 is the constant term c, which is the PRODUCT of the solutions, not their sum.

If you answered -6

−6 is b itself. The sum of the solutions is −b = 6.

More Advanced Math questions

• Very hard
  The function f(x) = x² + 6x + 5 is rewritten in the form f(x) = (x + a)² + b. What is the value of b?
• Very hard
  What is the solution to the equation 6/(x − 2) = 3?
• Very hard
  The polynomial p(x) = x³ − 4x has how many distinct real zeros?
• Very hard
  The polynomial p is defined by p(x) = x³ + ax² + bx − 12, where a and b are constants. If x − 2 is a factor of…
• Very hard
  The function f, defined by f(x) = 3000(1.331)^(x/12), gives the value, in dollars, of an investment x months a…
• Very hard
  In the xy-plane, the parabola y = x² − 4x + 7 and the line y = mx − 2, where m is a constant, intersect at exa…