Question

Find the domain and range for y=x^2+9.
Is the answer all real numbers? How would you enter that in interval notation? From Googling the definition of real numbers, I now understand that the infinity sign would not be included. For a continuous function you use closed brackets, but I just don't know what numbers to put into the brackets.

Is factoring something I should do here? I'm not sure.

Answer 1

for any x, x^2 >= 0
so, y >= 9 for all real x.
x can, of course, be any real number.

D: (-∞,+∞)
R: [9,+∞)

Answer 2

Thank you so much! That really helps. I totally forgot that the range would have to be over 9 due to the plus 9 in the equation.