domain s the numbers you can use
range is the result from putting the domain in
domain is all real numbers
range, see that -3x^2, all things become positive then negative
so highest thing would be at x=0, so then the highest thing in the range is 0
test another
x=3
the result is -27
0>-27
range is y≤0
domain=all real number
range is all real numbers less than or equal to 0
in interval notation
D=(⁻∞,∞)
R=(⁻∞,0]