SOLUTION: What's the domain and range of and show me how to get it 1)x(r)=3r^2-6+12 2)y=1/x-4 3)b(x)=7/-x^2

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Question 988697: What's the domain and range of and show me how to get it
1)x(r)=3r^2-6+12
2)y=1/x-4
3)b(x)=7/-x^2
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
I assume the first one is 3r^2-6R+12
at r=0 y=12
The vertex is -b/2a; r=1, from -(-6/6) That is the smallest value y will reach.
at r=1; y=3-6+12=9.
r has no bounds. Domain is all reals. Range is r> or equal to 9
graph%28300%2C300%2C-10%2C10%2C-10%2C20%2C3x%5E2-6x%2B12%29
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second can be done by graphing.
graph%28300%2C200%2C-10%2C10%2C-10%2C10%2C%281%2Fx%29-4%29
Domain is all x except x=0. Range is all y except y=4.
Note, if the problem is y=1/(x-4), I will just show the graph. It shifts it, but you get the same type of answer, only shifted.
graph%28300%2C200%2C-10%2C10%2C-10%2C10%2C1%2F%28x-4%29%29
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7/-x^2
x can be anything but zero
x^2 can never be negative, and -x^2 therefore can never be positive. The range is y (-oo,0). Y can never equal zero but approaches it asymptotically,
graph%28300%2C300%2C-10%2C10%2C-10%2C10%2C-7%2Fx%5E2%29