23+-+Sec.+9.3

Practice Problems Graphing The Quadratic Equation Main Idea: How to Graph Quadratic Equation Christina F Trisha K Arinna D The first thing that you want to look for is if a is positive and negative. If a is positive then the graph will open up. If a is negative then the graph will open down. Then you want to use -b/2a to find what the vertex is.c is where the graph should touch the y-axis.

__EXAMPLES__ -b/2(a)
 * Formula:**y=x^2+2x+1

Then I can find // k // by evaluating // y // at // h // =  –1/6 : //k =// 3( –1/6 )2 + ( –1/6 ) – 2 = 3/36 – 1/6 – 2 = 1/12 – 2/12 – 24/12 = –25/12  VERTEX:( –1/6, –25/12 ). GRAPH: y=-x^2+4x+1 a=(-1) b=4 c=1 x=-b/2a x=-4/2(-1) x=-4/-2=2 y=-(2)^2+4(2)+1 y=5 VERTEX (1,5) GRAPH: y= -3x 2 + x + 1 -b/2a = -(1)/(2(-3)) = 1/6. x=(1/6) y = -3x2 + x + 1 y = -3(1/6)2 + (1/6) + 1 y = -3(1/36) + (1/6) + 1 = y = -3/36 + 1/6 + 1 y = -1/12 + 1/6 + 1 y = 13/12, VERTEX:(1/6,13/12) GRAPH: = **Practice Problems** = **Graph (find the vertex first!)** 1. y=x^2-4x-4 3. y = -x^2 +2x-1 **
 * Ex.1** //h// = –//b///2//a// = –(1)/2(3) = –1/6
 * EX.2**
 * Ex.3**
 * 2. Y = x^2 - 1

