Question

Determine in which direction the parabola below opens. y = x2 - 7x + 18 A. left B. right C. up D. down

Answer 1

y=x2-7x+18

y''=2>0 opens up.

Answer C

Answer 2

opens up → C

given a parabola in standard form → y = ax² + bx + c ( a ≠ 0) then

• If a > 0 parabola opens up and has a minimum turning point

• If a < 0 parabola opens down and has a maximum turning point

y = x² - 7x + 18 has a = 1 > 0 thus opens up