You are here:

Algebra/Function Equation Help


Hey I got couple of function type questions I need you to show me how to do?

1.f(x)={x^2 if x<0
f(x)={x+1 if x≥0
Find f(-2), f(-1), f(0), f(1), f(2)

2. f(x)=x^2-9 and g(x)=√(9-x^2)
Find (fog)(x) and (gof)(x)

1. For this question, the only condition is if x >= 0 or x < 0.
For x=-2 and x=-1, x<0, so the answer is the first part of the function.
That is, it is x, and that gives f(-2) = 4 and f(-1) = 1.

For x=0, x=1, and x=2, we get f(x) = x+1, so the answers are
f(0) = 1, f(1) = 2, and f(2) = 3.

2. Isn't (fog)(x) the same as f(g(x))?
That means (gof)(x) would be the same as g(f(x)).

If g(x) = √(9-x), so putting this into f(x) = g(x) - 9 as g(x) gives f(g(x)) = 9-x - 9.
The 9's cancel, giving f(g(x)) = -x.

That also means that (gof)(x) would be the same as g(f(x)).
Since f(x) = x-9, this gives g(f(x)) = √(9-(x-9)).
In this case, that's all the farther we can go.  


All Answers

Answers by Expert:

Ask Experts


Scott A Wilson


Any algebraic question you've got. That includes question that are linear, quadratic, exponential, etc.


I have solved story problems, linear equations, parabolic equations. I have also solved some 3rd order equations and equations with multiple variables.

Documents at Boeing in assistance on the manufacturiing floor.

MS at math OSU in mathematics at OSU, 1986. BS at OSU in mathematical sciences (math, statistics, computer science), 1984.

Awards and Honors
Both my BS and MS degrees were given with honors.

Past/Present Clients
Students in a wide variety of areas since the 80's; over 1,000 of them have been in algebra.

©2017 All rights reserved.