Find the equation of the axis of symmetry of the graph of y = (x + 3)^2 - 5

1 answer:

3 0

Equation of the parabola: y = ax^2 + bx + c. Find a, b, and c.
x of axis of symmetry:
x
=
−
b
2
a
=
3
-> b = -6a
Writing that the graph passing at point (1, 0) and point (4, -3):
(1) 0 = a + b + c -> c = - a - b = - a + 6a = 5a
(2) -3 = 16a + 4b + c --> -3 = 16a - 24a + 5a = -3a --> a = 1
b = -6a = -6; and c = 5a = 5
y
=
x
2
−
6
x
+
5

Check with x = 1: -> y = 1 - 6 + 5 = 0. OK

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At the movies, a couple bought 2 medium drinks and a large popcorn for $13.85. At the same theater, a family bought 3 medium dri

yawa3891 [41]

Answer:

cost of one medium drink = $3.80

cost of one large popcorn = $6.25

Step-by-step explanation:

Let D = cost of one medium drink

Let P = cost of one large popcorn

If a couple bought 2 medium drinks and a large popcorn for $13.85:

⇒ 2D + P = 13.85

If a family bought 3 medium drinks and 2 large popcorn for a total of $23.90:

⇒ 3D + 2P = 23.90

Rewrite 2D + P = 13.85 to make P the subject:

⇒ P = 13.85 - 2D

Substitute into 3D + 2P = 23.90 and solve for D:

⇒ 3D + 2(13.85 - 2D) = 23.90

⇒ 3D + 27.7 - 4D = 23.90

⇒ D = 3.8

Substitute found value of D into P = 13.85 - 2D to find P:

⇒ P = 13.85 - (2 x 3.8) = 6.25

Therefore,

cost of one medium drink = $3.80

cost of one large popcorn = $6.25

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1 year ago

How do you complete the square to rewrite y= x^ -6x + 15 in vertex form

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Vertex form of a quadratic equation is $y=a(x-h)^{2}+k$
where (h, k) is the vertex.

Our aim is to write the expression $y=x^{2} -6x+15$ in the form
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$y=x^{2} -2*3*x+15$

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