-2(x-4)^2+1 in standard form
1 answer:
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Answer:
$21.2
Step-by-step explanation:
From the problem given, we express them as algebra so that we can easily solve;
the total charge on a call greater than 120min is given as;
120x + y(n - 120) = total cost of call
where n is the number of minutes which is greater than 120;
- Ethan paid $26.80 for 175 mins
n = 175min here;
120x + y(175 - 120) = 26.80
120x + 55y = 26.80 ----- (I)
- $32.40 for 210 minutes
n = 210min
120x + y(210 - 120) = 32.4
120x + 90y = 32.4 ----- (II)
Now let us solve both equations for y and x;
120x + 55y = 26.80 ----- (I)
120x + 90y = 32.4 ----- (II)
subtract the two equations;
90y - 55y = 32.4 - 26.8
35y = 5.6
y = = 0.16cents
then x;
120x = 26.8 - 55y from equation I
120x = 26.8 - 55(0.16)
120x = 18
x = = 0.15cents
Find the cost of 140min of talk time;
n =140min;
= 120(0.15) + 0.16(140 - 120)
= 18 + 0.16(20)
= 18 + 3.2
= $21.2
Answer:
Step-by-step explanation:
Let the quadratic equation of the function by the points in the given equation is,
f(x) = ax² + bx + c
If the points lying on the graph are (-3, -10), (-4, -8) and (0, 8),
For (0, 8),
f(0) = a(0)² + b(0) + c
8 = c
For a point (-3, -10),
f(-3) = a(-3)² + b(-3) + 8
-10 = 9a - 3b + 8
9a - 3b = -18
3a - b = -6 --------(1)
For (-4, -8),
f(-4) = a(-4)² + b(-4) + 8
-8 = 16a - 4b + 8
-16 = 16a - 4b
4a - b = -4 ------(2)
Subtract equation (1) from equation (2)
(4a - b) - (3a - b) = -4 + 6
a = 2
From equation (1),
6 - b = -6
b = 12
Function will be,
f(x) = 2x² + 12x + 8
= 2(x² + 6x) + 8
= 2(x² + 6x + 9 - 9) + 8
= 2(x² + 6x + 9) - 18 + 8
= 2(x + 3)² - 10
By comparing this function with the vertex form of the function,
y = a(x - h)² + k
where (h, k) is the vertex.
Vertex of the function 'f' will be (-3, -10)
And axis of symmetry will be,
x = -3
From the given graph, axis of the symmetry of the function 'g' is; x = -3
Therefore, both the functions will have the same axis of symmetry.
y-intercept of the function 'f' → y = 8 Or (0, 8)
y-intercept of the function 'g' → y = -2 Or (0, -2)
Therefore, y-intercept of 'f' is greater than 'g'
Average rate of change of function 'f' = in the interval [a, b]
=
=
= -6
Average rate of change of function 'g' =
=
=
= 3
Therefore, Average rate of change of function 'f' is less than 'g'.