1. Factor out the coefficient of $x^2$ from the $x$ terms
2x2−3x−11=2(x2−23x)−11
2. Complete the square for the expression inside the bracket
=2[(x−43)2−(43)2]−11
=2[(x−43)2−169]−11
3. Expand and simplify to reach the required form
=2(x−43)2−2(169)−11
=2(x−43)2−89−888
=2(x−43)2−897
4. State the coordinates of the turning point
The turning point of y=a(x−h)2+k is (h,k).
Turning point = (43,−897)
答案2(x−43)2−897
Turning point: (43,−897)