3.3c Sketching the Graph of Quadratic Functions (Example)

Example 1
Express $y=5+4x-x^2$   in the form $y=a-{(x+b)}^2$   , where a, b, and c  are constants. Hence state the maximum  value of y and the value of x at which it occurs. Sketch the curve $y=5+4x-x^2$   .