190k views
0 votes
Piecewise function question please help!

Piecewise function question please help!-example-1
Piecewise function question please help!-example-1
Piecewise function question please help!-example-2
Piecewise function question please help!-example-3
Piecewise function question please help!-example-4

2 Answers

4 votes

Answer: Choice B

=====================================================

Step-by-step explanation:

The endpoint (-7,-5) reflects over the line y = x when forming the inverse. It will reflect to (-5,-7). The x and y coordinates swap.

The new point (-5,-7) forms the vertex of a piece of a parabola. Since it's the vertex, we have something of the form y = a(x+5)^2 - 7 which matches with choices B and D.

However, we can rule out choice D because the interval is not x < -3. Try out a point like x = -100 and it will make x < -3 true, but -100 is definitely not part of the reflected parabola formed. Instead, we must have -5 < x < -3 as the domain of the inverse.

Notice how the range of the square root portion on the left is -5 < y < -3. The range of the original function forms the domain of the inverse, and vice versa. Effectively, all we're doing is replacing y with x when going from -5 < y < -3 to -5 < x < -3.

--------------

Also another reason we can rule out choice D is to see that something like x = -2.5 will make log(x+2) to result in a non-real number. This is due to the fact that the domain of log(x) is x > 0. So the domain of log(x+2) is x > -2.

User Reckface
by
3.5k points
13 votes

Answer:

b

Step-by-step explanation:

We know we are trying to find an inverse function and the normal function of the first part would be (x+7)²-5, so we can eliminate all equations with an equation starting with (x+7)²-5. So, a and f are out of the scope.

The domain of the inverse function will be the range of the normal function.

So, the range of the first part of the inverse function is -5 < x < -3 which is the domain of the normal function. Now, we can eliminate c, d, and e.

Our answer must be b.

User Rizwan Gill
by
3.5k points