Our parent function is f(x)=x^2. A vertical stretch by a factor of k means that every point (x,f(x)), has been transformed into (x,kf(x)). Alex is clearly incorrect as our parent function has been transformed to (x,9f(x)), not (x,3f(x)). A horizontal stretch(or compression) by a factor of k means our function has been transformed to (x/k,f(x)). Here, Marta is saying our function should look like (3x,f(x)). This can also be achieved by plugging 3x into the parent function, which would give us f(3x)=(3x)^2, so it seems that Marta is the correct one.
Problem 1
Answer: Choice B. X is greater than or equal to 4
The closed circle at 4 indicates that this value is included in the solution set. So we will have an "or equal to" as part of the answer. The shading to the right suggests "greater than". Combine "greater than" and "or equal to" and we have a "greater than or equal to" sign.
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Problem 2
Everywhere is shaded but -4 on the number line. So x can be any number but -4. The answer isn't listed (probably got cut off), but it should be 
(x is not equal to -4). The slash through the equal sign means "not equal to"
No expressions are showing to choose from, but it should look like:
A= amount of money earned
m= # of miles driven
Amount earned equals $6 plus ($0.45 times the # of miles driven.)
EQUATION:
A= $6 + $0.45m
Hope this helps! :)
Answer: 288.17
Step-by-step explanation:
y ∝ x
⇒ y = kx
substituting the given value of x and y , the equation becomes
12 = 14 k
therefore
k = 12/14
k = 6/7
The formula then becomes
y = 6/7 x
when y = 247, we have
247 = 6/7 x
6x = 247 x 7
6x = 1729
x = 1729/6
x = 288. 17
