What is the maximum or minimum value of f(x) = -x2 + 2x - 8

Answer 1

-2x^2 +2x -8 complete the square

-2(x^2 -x+ 1/4) - 8 +1/2

-2(x-1)^2 -7.5

-7/5 = global and local maximum = the y coordinate of the vertex of a downward opening parabola

or use calculus

derivative = -4x +2 = 0, x = 1/2

-2(1/2)^2 +2(1/2) - 8 = -1/2 -7 =- 7.5

or using a graphing calculator and visually see the maximum

thee are no minimums local or global