230 likes | 246 Views
Unit 1B quadratics. Day 3. Graphing a Quadratic Function EQ: How do we graph a quadratic function that is in vertex form?. M2 Unit 1B: Day 3. Lesson 3.1B. Vertex Form. Tells us the direction in which the parabola opens. Provide the coordinates of the vertex: (h, k).
E N D
Unit 1Bquadratics Day 3
Graphing a Quadratic FunctionEQ: How do we graph a quadratic function that is in vertex form? M2 Unit 1B: Day 3 Lesson 3.1B
Vertex Form Tells us the direction in which the parabola opens Provide the coordinates of the vertex: (h, k) ** NOTE: Always change the sign of h
First, we must be able to identify a, h, and k in each quadratic function. a = 2 h = 3 k = 1 a = -1 h = -2 k = -4 4
Name the vertex of each quadratic function and determine if the parabola opens up or down. a = -2 h = 3 k = 4 a = 1 h = -1 k = 2 Vertex is (3,4) Vertex is (-1,2) Parabola opens down Parabola opens up Vertex is (-4,0) Vertex is (0,0) Parabola opens down Parabola opens up 5
Y-intercept of a Quadratic Functions To find the y-intercept, substitute zero for each x in the equation Example 3 Find the y-intercept for 6 Course 3
Y-intercept of a Quadratic Functions Example 4 Find the y-intercept for 7
Find the y-intercept of the given Quadratic Functions The y-intercept is -14 or (0, -14) The y-intercept is 3 or (0, 3)
In order to graph using vertex form: • Find the axis of symmetry and sketch it. • Find the vertex, then plot it. • Find the y-intercept, then plot it and its “twin” or “mirror image” • Find another point and its “mirror image” 9
maximum minimum Extrema – y-coordinate of the vertex Maximum – the Vertex when the parabola opens down • Minimum – the vertex when the parabola opens up 10
Graph the quadratic using the axis of symmetry and vertex. a = 2 h = 1 k = 3 Opens UP Vertex: (1, 3) Minimum at y = 3 Axis of symmetry: Y-intercept: (0, 5) One more point: (3, 11) 11
Graph the quadratic using the axis of symmetry and vertex. a = -1 h = -1 k = -1 Opens DOWN Vertex: (-1, -1) Maximum at y = -1 Axis of symmetry: Y-intercept: (0, -2) One more point: (1, -5) 12
Graph the quadratic using the axis of symmetry and vertex. a = 1 h = 2 k = 0 Opens UP Vertex: (2, 0) Minimum at y = 0 Axis of symmetry: Y-intercept: (0, 4) One more point: (1, 1) 13
Graph the quadratic using the axis of symmetry and vertex. a = -1 h = -3 k = -2 Opens DOWN Vertex: (-3, -2) Maximum at y = -2 Axis of symmetry: Y-intercept: (0, -11) One more point: (-2, -3) 14
Ex7. How would you translate the graph of to produce the graph of ? Old vertex: (0, 0) New vertex: (-2, -1) Translate left 2 units and down 1 unit. *Focus on how the vertex shifts!
9. How would you translate the graph of to produce the graph of ? Old vertex: (0, 0) New vertex: (1, 5) Translate right 1unit and up 5 units.
MM2A3 Students will analyze quadratic functions in the forms f(x) = ax2 +bx + c and f(x) = a(x – h)2 = k. f(x) DomainThe domain of a function is the set of all possible input values, x, which yield an output x y RangeThe range of a function is the corresponding set of output values, y. 17
Domain VS. Range • Domain: (x – values) read domain from left to right • Range: (y-values) read range from bottom to top
Find the domain and range of the quadratic Function. f(x) = x2 + 1 Domain: all real numbers Range: y ≥ 1 (the set of all real numbers greater than or equal to 1) 19
Find the domain and range of the quadratic Function. f(x) = (x - 2)2 + 5 Domain: all real numbers Range: y ≤ 5 (the set of all real numbers less than or equal to 5) 21
Find the domain and range of the quadratic Function. f(x) = - (x + 2)2 - 1 Domain: all real numbers Range: y ≥ -1 22
Assignment • 3.2 Practice WS (#1-12 all)