Given:
y varies directly with x,
It is given that y = 7 when x = -9.
To find:
The value of y when x = 27 for the direct variation.
Solution:
It is given that y varies directly with x, so
...(i)
Where, k is the constant of proportionality.
It is given that y = 7 when x = -9. Putting these values in (i), we get
Putting in (i), we get
Putting , we get
Therefore, the required value is .
Answer:
First, let's define the transformations in a general way.
Vertical translation:
A vertical translation of N units is defined as:
g(x) = f(x) + N
if N is positive, the translation is up
if N is negative, the translation is down.
Horizontal translation:
A horizontal translation of N units can be written as:
g(x) = f(x - N)
if N is positive, the translation is to the right
if N is negative, the translation is to the left.
Reflected vertically (or a reflection over the x-axis)
This type of reflection changes the sign of the y component.
We can write those as:
g(x) = -f(x)
Then:
We start with the function:
f(x) = 2^x
First we reflect it vertically.
g(x) = -2^x
now we do a vertical translation of 5 units up, then:
g(x) = -2^x + 5
Now we do a translation of 3 units to the left, then we get:
g(x) = - 2^(x + 3) + 5
Then we already did the first step.
Now we want to find the domain for this function, the domain will be the set of the possible values of x that we can input in the function g(x).
Notice that in this function the denominator is never zero, so there are no values of x that generate problems here, so the domain will be the set of all real numbers, that can be written as:
(-∞, ∞)
3) Now we want to find the range, this is the set of the possible values of g(x).
The Largest value of g(x) will be when the exponential part tends to zero, this is for really small values of x, such that when x goes to minus infinity, -2^(x + 3) goes to zero.
Then:
g(-∞) ≈ 5
The maximum of the range is 5.
And we do not have a minimum, because as x increases the function will decrease infinitely.
Then the range will be:
(-∞, 5)
(A graph of the function can be seen below)
