Differentiate it
get f ' (x)=3x^2-4
put 3x^2-4=0
x=2/√3,-2/√3
so interval
x∈(-2/√3,2/√3)
Answer:
15,17,19
Step-by-step explanation:
Make an equation : 
Solve the equation:



Since x=15 then the second number is 17 and then 19
Hope this helps!
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Y=1.5 at the midpoint of GH. To do this you add the y values of the endpoints together and divide by two ----> 5-2= 3 ----> 3/2= 1.5
Hope this helps you !!
The answer will be for every x, y will be 1.25