Question 206260
The base function is {{{y=x^2}}}
"a range consisting of all numbers less than or equal to 4"
The parabola must open downwards because of less than or equal.
{{{y=-x^2}}}
But, {{{y=-x^2}}} has a range of (-infinity, 0].  So you need to shift it up 4.

{{{y=-x^2+4}}}
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"x-intercepts -1 and 3"
The normal x intercepts for {{{y=-x^2+4}}} would be -2, 2.
You need to shift the parabola to the right 1 to get -1, 3.
{{{y=-(x-1)^2+4}}}