What is the equation of a parabola that has a vertex at ( 0,4 ) and passes through points ( 2,0 )?
1 answer:
Answer:
<u>y = -x² + 4</u>
Step-by-step explanation:
The equation of the parabola in the vertex form is:
y = a (x-h)² + k
Where: (h,k) the coordinates of the vertex & a is a multiplier
The parabola has a vertex at ( 0,4 )
So, h = 0 , k = 4
∴ y = a (x-0)² + 4
∴ y = a x² + 4
The parabola passes through points ( 2,0 )
∴ 0 = a 2² + 4
∴ 4 a = -4 ⇒ a = -4/4 = -1
∴ y = -x² + 4
So, the equation of a parabola that has a vertex at ( 0,4 ) and passes through points ( 2,0 ) is <u>y = -x² + 4</u>
See the attached figure.
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Answer:
y = -2x - 2
Step-by-step explanation:
From the graph attached,
If the line 'l' passes through two points A(0, -1) and B(4, 1).
Rule for the rotation of any point (x, y), 90° clockwise about the origin is,
(x, y) → (y, -x)
By this rule,
A(0, -1) → A'(-1, 0)
B(4, 1) → B'(1, -4)
Let the equation of the line A'B' is,
y - y' = m(x - x')
where m = slope of the line A'B'
And (x', y') is a point lying on the line.
Slope of the line passing through A' and B' will be,
m =
m =
m = -2
Therefore, equation of the line passing through (-1, 0) and slope = -2,
y - 0 = (-2)(x + 1)
y = -2x - 2
So the equation of the line after rotation of lie 'l' by 90° clockwise will be,
y = -2x - 2
