The x-intercepts are the values of x for which f(x) = 0.
x^2 + 4 = 0
x^2 = -4
x= ±√(-4), which are not real numbers. f(x) does not have an x-intercept.
Let's write miles over hours
80 / 2 = 200/ x
cross multiply
80x = 400
divide both sides by 80
x = 5
It will take 5 hours to cover 200 miles
Hope this helps :)
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F(x) sqrt x+4 (the last one) is your answer!!!