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Graphing. Graph:. NOTE: Here are some more like this: y = x y = 1.2 x y = 1/3 x y = 4 x. y = - 3x. THEY ALL HAVE A “x” and a “ y “ but NOTHING added or subtracted to them. x = (0,0). y = (0,0). MAKE a “t” chart to help you graph this type. m = -3. y. x. -3 -6 -9. 1 2 3.
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Graph: NOTE: Here are some more like this: y = x y = 1.2 x y = 1/3 x y = 4 x y = - 3x THEY ALL HAVE A “x” and a “ y “ but NOTHING added or subtracted to them x = (0,0) y = (0,0) MAKE a “t” chart to help you graph this type m = -3 y x -3 -6 -9 1 2 3
Graph: NOTE: IT DOES NOT have an “x” ! y = -4 x = none y = (0,4) m = 0
Graph: NOTE: IT DOES NOT have an “y” ! x = -3 x = (-3,0) y = none m = undefined
Solve for y: NOTE: This is NOT the same as “find the y intercept”! y-2 = - 3(x+2) Distribute the - 3 y-2 = - 3x + - 6 Add 2 to both sides y = - 3x + - 4 DONE
Find the y intercept: LET x = 0 and evaluate! y-2 = - 3(x+2) y-2 = - 3(0+2) y-2 = - 3(2) y-2 = - 6 HEY!!! What is the slope of this line? y = - 4
Consider…. 4x – 6y = 36 You’re finding the y intercept because you let x equal zero! If I do this next step….what am I finding? Why? 4(0) – 6y = 36 If you find the x and y intercepts you can use the SLOPE FORMUAL OR…. What is the slope of this linear equation? You could solve for y and get this standard form into the slope intercept form! m: 4/6 or 2/3
Consider…. It graphs a parabola BECAUSE the degree of the polynomial is a 2! y = - 4(x – 3)2 What does this graph? How do you know that? It flips DOWN because the 4 is NEGATIVE! Does this graph flip up or down? How do you know this? What are the coordinates of it’s vertex? (3, 0) Find it’s x intercept(s)? 0 = - 4(x – 3)2 0 = - 4(x – 3)2 Divide both sides by -4 and then square root both sides. 0 = x – 3 Add 3 to both sides. x-intercept is (3,0)
Consider…. It graphs a parabola BECAUSE the polynomial has TWO x’s! y = (x + 4)(x – 3) What does this graph? How do you know that? Because it is factored AND equal to zero, we can set both factors equal to zero and solve! Find the x intercepts 0 = (x + 4)(x – 3) 0 = (x + 4) 0 =(x – 3) x = -4 x =3 X: (-4, 0) (3, 0)
Add the x intercepts together and divide by 2! y = (x + 4)(x – 3) How can you find the vertex IF you KNOW the x intercepts? This gives you the x-coordinate of the vertex. Substitute this value into the equation to determine the y-coordinate. = (- -11.25 y = (1/2 + 4)(1/2 – 3) y = (1/2 + 4)(1/2 – 3) y = -11.25
Consider…. Either factoring or Q.F. y = x2 + x - 12 What “tools” would you use to find the x intercepts? Because it’s a trinomial, the leading coefficient is 1 it is easy to factor! y = (x + )(x+ ) -3 4 We need two factors of – 12 that add to 1 4 and – 3 multiply to -12 and ADD to 1 To finish this one, we would set the factors equal to zero and solve the equations! Just like we did on the quadratic before this one!
Consider…. Either factoring or Q.F. y = 5x2 + x - 2 What “tools” would you use to find the x intercepts? It doesn't factor so What does it mean if the determinate turns out to be NEGATIVE? That there are NO real x-intercepts!!!
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