SOLUTION: Please help me. I have no clue on what numbers to use for this parabola since my Y intercepts come out as big numbers. I need to sketch the parabola with the equation 4x^2-16x+15

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Please help me. I have no clue on what numbers to use for this parabola since my Y intercepts come out as big numbers. I need to sketch the parabola with the equation 4x^2-16x+15       Log On


   



Question 897132: Please help me. I have no clue on what numbers to use for this parabola since my Y intercepts come out as big numbers.
I need to sketch the parabola with the equation 4x^2-16x+15 and label the vertex, axis of symmetry, x and y intercepts. Should I divide by 4?

Found 3 solutions by rothauserc, MathTherapy, richwmiller:
Answer by rothauserc(4718) About Me  (Show Source):
Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!
Please help me. I have no clue on what numbers to use for this parabola since my Y intercepts come out as big numbers.
I need to sketch the parabola with the equation 4x^2-16x+15 and label the vertex, axis of symmetry, x and y intercepts. Should I divide by 4?

Standard form of a parabolic equation: y+=+ax%5E2+%2B+bx+%2B+c
The x-coordinate of the vertex occurs at: x+=+-+b%2Fa. This is also the axis of symmetry.
The y-coordinate of the vertex occurs at: f%28x%29+=+4x%5E2+-+16x+%2B+15, where x is the value of the x-coordinate of the vertex
The x intercepts, or roots occur at the solutions to: 4x%5E2+-+16x+%2B+15+=+0
The y-intercept occurs at f%280%29+=+4x%5E2+-+16x+%2B+15. Looking at the equation, it should be: 15
**FYI
If you intend to create the vertex form of the equation, then you'd need to divide through by 4.
Otherwise, that's too much work.

Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
y=4x^2-16x+15
y = (2x-5)*(2x-3)
let x=0 y=15
let x=1 y=3
let x=2 y=-1
min{y = 4 x^2-16 x+15} = -1 at x = 2
parabola
focus | (2, -15/16)~~(2, -0.9375)
vertex | (2, -1)
semi-axis length | 1/16 = 0.0625
focal parameter | 1/8 = 0.125
eccentricity | 1
directrix | y = -17/16