How do you use the important points to sketch the graph of #y=x^2-4x+5#?

1 Answer
May 20, 2016

Please see below.

Explanation:

An equation of the type #y=ax^2+bx+c# is the equation of a parabola.

  1. The first thing is to identify axis of symmetry, which in above form is given by #x=-b/2a#. Here we have #y=x^2-4x+5# and hence axis of symmetry is #x=(-(-4))/2=2#.
  2. Further, as coefficient of #x^2# is positive and at #x=2# #y=2^2-4*2+5=1#, it has a minima at #(2,1)#
  3. At #x=0#, #y=5# hence it passes through #(0,5)#
  4. Other points may be found around #x=2# and these are #(-3,26)#, #(-2,17)#, #(-1,10)#, #(1,2)#, #(3,2)#, #(4,5)#, #(5,10)#, #(6,17)#, #(7,26)#.

The parabola looks like

graph{x^2-4x+5 [-7.375, 12.625, -1.8, 8.2]}